The main difference between Seraph and Archangel is that the Seraph is a type of angel in Judaism and Christianity and Archangel is a angel of high rank
A seraph (, “the burning one”/”serpent”; or seraphim , in the King James Version also seraphims (plural); Hebrew: שָׂרָף śārāf, plural שְׂרָפִים śərāfîm; Latin: seraphim and seraphin (plural), also seraphus (-i, m.); Greek: σεραφείμ serapheím Arabic: مشرفين Musharifin) is a type of celestial or heavenly being originating in Ancient Judaism. The term plays a role in subsequent Judaism, Christianity, and Islam. The singular “seraph” is a back-formation from the Hebrew plural-form “seraphim”, whereas in Hebrew the singular is “saraph”.Tradition places seraphim in the highest rank in Christian angelology and in the fifth rank of ten in the Jewish angelic hierarchy. A seminal passage in the Book of Isaiah (Isaiah 6:1–8) used the term to describe six-winged beings that fly around the Throne of God crying “holy, holy, holy”. This throne scene, with its triple invocation of holiness (a formula that came to be known as the Trisagion), profoundly influenced subsequent theology, literature and art. Its influence is frequently seen in works depicting angels, heaven and apotheosis. Seraphim are mentioned as celestial beings in an influential Hellenistic work, the Book of Enoch, and the Book of Revelation.
An archangel is an angel of high rank. The word “archangel” itself is usually associated with the Abrahamic religions, but beings that are very similar to archangels are found in a number of religious traditions.
The English word archangel is derived from the Greek ἀρχάγγελος (arch- + angel, literally “chief angel” or “angel of origin”). It appears only twice in the New Testament in the phrase “with the voice of the archangel, and with the trumpet call of God” (1 Thessalonians 4:16) and in relation to “the archangel Michael” (Jude 9). The corresponding but different Hebrew word in the Hebrew Scripture (Old Testament) is found in two places as in “Michael, one of the chief princes” (Dan 10:13) and in “Michael, the great prince” (Dan 12:1).
A six-winged angel; the highest choir or order of angels in Christian angelology, ranked above cherubim, and below God. They are the 5th highest order of angels in Jewish angelology. A detailed description can be found at the beginning of [http://en.wikisource.org/wiki/Bible_%28World_English%29/Isaiah#Chapter_6 Isaiah chapter 6]
A powerful angel that leads many other angels, but is still loyal to a deity. (Judeo-Christian examples: Gabriel, Michael, Raphael, Uriel).
In Christian angelology, an archangel is an angel from the third level or choir of angels, ranked above virtues and below powers.