This is a truly expansive topic, and I'm not sure I can give it justice in any sense in the short time I can give it with the very limited knowledge of the Bible that I have, but I'll try as I see it as central to understanding the mechanics of the Gospel preaching and harvest.
First, I'm no expert on Greek, so I apologize to those who are if I step on some toes, but it appears to me that if there is no difference in the verbs in the Greek text to give you guidance here, you are faced with two choices: either to accept the notions of "general" and "effectual" call based on the wider view of election presented in the Bible at large or reject the terms as "unbiblical."
To me the distinction made by the early Reformers and later in creeds seems sound (as in "biblical"). It would be similar to a case that can be made concerning the use of terms like "trinity" or "omnipresence" of God: while the terms are missing from the original (OT and NT) text, the use of those terms can be easily justified as a shorthand for what is clearly stated in the Bible about the "attributes" of God referenced by those "non-biblical" terms...
As far as the actual terms ("general" vs "effectual" call), based on both OT and NT text a case can be made that there is a distinction between the two based on their respective outcomes: while the "general" call refers to the preaching of the Gospel that goes out to all, the Gospel is only accepted by the elect who can be thus said to have received the "effectual" call.
A couple of "textbook" examples can be used here to show both calls at work (although once you start reading the Bible closely, you can see both on nearly every page):
Exhibit 1: Jesus' calling of the 12. All 12 (and many more) heard the "general" call to be Jesus' disciples, but then many who had initially accepted that call turned away when following Jesus became "too costly" (Jesus' "harsh sayings," his rejection by the religious establishment of the day and the resulting castigation of those who chose to follow Jesus, etc. (e.g. see John 6:66). The departure culminated in the betrayal of one of the 12 — Judas. While commenting on the latter (John 6:70):
Jesus answered them, Have not I chosen you twelve, and one of you is a devil? He spake of Judas Iscariot the son of Simon: for he it was that should betray him, being one of the twelve.
In other words, Jesus himself said that he "chose" (Gr. eklégomai, I realize that it's not the root word you were looking at in your question, but I think both "calling out" and "choosing out" are similar enough verbs to be studied together in connection with your research of God's call to salvation) the 12, and yet one of the 12 was "the devil." Obviously the Reformers (following the lead of the NT writers themselves, I'd claim) would conclude that Judas was an example of someone who heard the general call but didn't receive the effectual call, hence his ultimate (inevitable) falling away. By contrast, when the disciples were pressed by Jesus on whether they wanted to likewise depart and abandon their call, Peter (acting as a "spokesman" — as per usual arrangement — exclaimed (John 6:68):
[...]Lord, to whom shall we go? thou hast the words of eternal life.
Thus, those who received the effectual call didn't want to leave (one could even say wouldn't or couldn't leave) in the ultimate sense because they were "born again" and as such were "captured" as it were by the effectual call. They couldn't become "unborn" as they came from "death to life" and would remain alive forevermore (e.g., see John 6:39-40). To wit, even though Peter would later betray Jesus much like did Judas, we can judge — based on the fact that since Peter (unlike Judas) repented of his betrayal, was restored, and returned to fruitful ministry in God's vineyard (the Church) — that Peter was called with the effectual call of which he himself testifies (2 Peter 1:1, Legacy Bible):
Simeon Peter, a slave and apostle of Jesus Christ, To those who have received the same kind of faith as ours, by the righteousness of our God and Savior, Jesus Christ...
Exhibit 2: Ap. Paul provides the most eloquent discourse on the two types of call found in the Bible in his doctrinal magnum opus (Romans chs 9-11, a must-read/study for anyone trying to understand how God's calling works). There Paul speaks of the Gospel being preached to the Israelites (Romans 10:16-18):
But they have not all obeyed the gospel. For Isaiah says, “Lord, who has believed our report?” So then faith comes by hearing, and hearing by the word of God. But I say, have they not heard? Yes indeed: “Their sound has gone out to all the earth, And their words to the ends of the world...”
If you read the rest of the apostle's discourse, it becomes clear that God's election stands in spite of the fact that "some" rejected (and continue to reject) the Gospel. The effectual call, by the way, is given an exhaustive and "unbreakable" (from God's foreknowledge in eternity past all the way to the glorification of the saints at his Second Coming — Hallelujah!) description earlier in the epistle (Romans 8:30):
Moreover whom He predestined, these He also called; whom He called, these He also justified; and whom He justified, these He also glorified.
Again, much more can be said, but I think this is a good place to start answering your question. I highly recommend the said passages from Romans as well as chs 5-10 of John's Gospel if you want to understand the difference between the two types of calling as accepted by the Bible writers and the Reformers...
On the final note, if it's helpful to you to use the terms "general" and "effectual" call to converse with like-minded believers, I think there is no harm there as the terms provide a useful shorthand for certain points of sound Biblical doctrine. On the other hand, if you get into a conversation with those who disagree with you on the subject of God's sovereign election, I would stay away from such terminology and just use the relevant Bible verses (and Greek verbs :) instead.
Edit: There are some quotes to be found from earlier Reformed luminaries like Luther and Calvin (I'll still try to look into finding those), but here you can find a selection from a later (Spurgeon) era. It was put together by Ligonier Ministries. They can usually be counted on when it comes to such essentials of the Reformed theology as the Five Solas or election...