Regarding these words as used to form temporal phrases/clauses:
1. 'Since' is both a conjunction and a preposition, whereas 'from' is only a preposition. Thus, both clauses and prepositional phrases can be formed with 'since', while only the latter can be formed with 'from'.
2. A since-clause/phrase relates typically to a present-anterior or past-anterior time frame. (The former is one viewed as extending from a point in past time up to the present time of utterance, and the latter one viewed as extending from a point in remote past time up to the past time of reference). That is to say, it typically modifies only present perfect or past perfect verb phrases (in either simple or progressive forms), as in
I have been studying since I got home*.
(= I started studying when I got home and am still doing so at the present moment.)
They had not seen each other since 1939.
(= 1939 was the last time that they had seen each other prior to the past time in which the narrative is set.)
A from-phrase, on the other hand, relates to a past, present or future time frame, as in
I lived there from 1973 to 1985.
(a past time frame)
I work from nine to five every day.
( a present time frame)
I'm going to be away from the 16th to the 23rd.
(a future time frame).
A from-phrase is always (at least implicitly) complemented by a to-phrase, needed to specify the end-point of the period in question (unnecessary in the case of a since-phrase, whose end is naturally specified, as noted above, by either the time of utterance or the time of reference).
*You'll also see from this that, although a since-phrase/clause cannot modify a past simple verb phrase, it can nevertheless contain one.