According to one of my books (correct me please), the M1 fired a .30 round.
When the NATO 7.62 round came into use, the M-1 was used as the basis for the new rifles. The final Trial rifle, the T-44, is what we know as the M-14.
The M-14 has a 20 round (detachable?) mag, as opposed to the M1A 15 round, or the M1 Garand's 8 round.
It also featured select-fire, which was dropped after there were a few problems.
There was also the M-14A1 which had a bipod, and pistol/fore grips.
When the M-16 came into service, a lot of M-14s were sold to the Isrealis until they got the Galil.
(Also according to this, the Mini-14 was meant to be a version by Ruger for 5.56.)
(could be wrong on a lot of this, check please.)