They fire the same round.
The M1A and the Ruger Mini-30 do NOT shot the same ammunition.
M1A is better made and shoots the .308 (7.62x51mm NATO round).
The Mini is well made but is built using looser tolerances. The Mini-30 shoots the Russian 7.62X39. At 600 yards the M1A will get the same MOA as the mini30 at 100 yards.
Besides the ammunition differences, the Mini-30 is not as accurate as the M1A.