Question: Based on Hebrews 1:5 and 13 you ask how Jehovah's Witnesses can say that Jesus is the archangel Michael. You also ask, what is the distinction between the Son of God and the angels?
In order to find an answer it is necessary to first understand what Jehovah’s Witnesses believe regarding the relationship between Jesus Christ, the Son of God, and the archangel Michael. Here is a brief overview, using only quotations from their own literature:
New Heavens and New Earth pages 30-31: "It proves Michael the archangel is none other than the only begotten Son of God, now Jesus Christ. The very name Michael means ‘Who is like God?’ and indicates Jehovah God is without like or equal." 
Your Will be Done on Earth page 316: “Jesus is actually the incarnation of Michael the archangel and resumed the name when he ascended into heaven.” 
What Does the Bible Really Teach pages 218-219: "The Bible indicates that Michael is another name for Jesus Christ, before and after his life on earth... Since God's Word nowhere indicates that there are two armies of faithful angels in heaven - one headed by Michael and one headed by Jesus - it is logical to conclude that Michael is none other than Jesus Christ in his heavenly role." 
"Who, though, was the son whom God chose to be born as a perfect human creature? ...He has rightly been called Michael the Archangel. His life-force having been transferred to Mary's egg cell by Almighty God's power that overshadowed Mary meant that he, Michael, disappeared from heaven. By human birth from Mary, the Jewish virgin, he was to become a human soul." (God's "Eternal Purpose" Now Triumphing, 1974, pp 137-138)
What does the Society teach that this "life-force" is? "The word 'spirit' is translated from the Hebrew word ru'ach, meaning the life-force that animates all living creatures, human and animal. (Ecclesiastes 3:18-22) However, the important difference is that ru'ach is an impersonal force; it does not have a will of its own or retain the personality or any of the characteristics of the deceased individual." (Mankind's Search for God, 1990, pp 153-154)
In an attempt to find evidence to support the suggestion that Jesus is in a different class than any other angel, I went to the official Jehovah’s Witness web site and searched on angels:
Insight on the Scriptures, Volume 1, pages 106-108, Angel Order and Rank: “As with the visible creation, so also in the invisible realm there is order and rank among the angels. The foremost angel, both in power and authority, is Michael, the archangel.”
The article goes on to mention Seraphs: “Ranking very high among the angels in privileges and honor are the seraphs.” Cherubs also “hold a special position among the angels.” “Then there is the great body of angelic messengers who serve as a means of communication between God and man.” https://wol.jw.org/en/wol/d/r1/lp-e/1200000277?q=angel+order+rank&p=par
No mention of any other class of angel. Michael the archangel is the most powerful, then there are Seraphs and Cherubs and Gabriel is also mentioned in Scripture as a messenger. The demons are classified as fallen angels, angels who sinned. From here I searched on Son of God:
Insight on the Scriptures, Volume 2, pages 393-394: “Scriptural evidence indicates that the name Michael applied to God’s Son before he left heaven to become Jesus Christ and also after his return…  Michael is actually the Son of God.” 
“In his prehuman existence Jesus was called “the Word.” (Joh 1:1) He also had the personal name Michael. By retaining the name Jesus after his resurrection (Ac 9:5), “the Word” shows that he is identical with the Son of God on earth.  His resuming his heavenly name Michael and his title (or name) “The Word of God” (Re 19:13) ties him in with his prehuman existence. The very name Michael, asking as it does, “Who Is Like God?” points to the fact that Jehovah God is without like, or equal, and that Michael his archangel is his great Champion or Vindicator.” https://wol.jw.org/en/wol/d/r1/lp-e/1200003035?q=Michael+Son+God&p=par
Watchtower 1 April 2010: Is Jesus the Archangel Michael? Put simply, the answer is yes ... In view of the foregoing, what can we conclude? Jesus Christ is Michael the archangel. Both names—Michael (meaning “Who Is Like God?”) and Jesus (meaning “Jehovah Is Salvation”)—focus attention on his role as the leading advocate of God’s sovereignty. Philippians 2:9 states: “God exalted him [the glorified Jesus] to a superior position and kindly gave him the name that is above every other name.” So Michael the archangel is Jesus in his prehuman existence. After his resurrection and return to heaven, Jesus resumed his service as Michael, the chief angel, “to the glory of God the Father.”—Philippians 2:11. Source: https://wol.jw.org/en/wol/d/r1/lp-e/2010250 
This last quotation offers a clue as to how Jehovah’s Witnesses perceive the status of the glorified Jesus. As one Jehovah’s Witness put it, “Jesus is stated to have been previously at par with the angels, but now he has been glorified above them. Therefore, he is excluded from the angels.” I take that to suggest that since the glorified Jesus has now been exalted to a position higher than all the angels then the quotation from Psalm 2:7 isn’t referring to Jesus as an angel because the Son of God has been exalted and glorified and is higher than any of the angels.
The fatal flaw in this argument, however, is that quotes from two Jehovah’s Witness publications say Michael is the Son of God  and Jesus was the incarnation of Michael the archangel when he was born of Mary . Since they believe that Jesus was known as Michael the archangel before and after he came to earth  then I can only assume that Jesus is still an archangel. Of course, there is an argument that because the pre-human Jesus was the only spirit creation of Jehovah God, then that makes him special, and different to all the other angels that were created by and through Jesus. Personally, I don’t go along with that sort of “reasoning” but there may be an article on the subject.
I’ve spent hours trawling through jw.org but can’t find anything that specifically addresses the issue raised by Hebrews 1:1-14. Perhaps a Jehovah’s Witness will be able to track one down. For the avoidance of doubt, I am not promoting the beliefs of Jehovah’s Witnesses.