Soviet tank designations are a terrible mess, esp. when locals come into play as well
Just to illustrate this, Czechoslovakian T-72's:
T-72 Obiekt 172M-E (first batch delivered from Soviet union) - really called T-72. So far so good.
T-72M Obiekt 172M-E2 (T-72's manufactured here, already have T-72A/M front hull, laser RF, but lack skirts and smoke greandes - mostly) - really called T-72 by our army
T-72M Obiekt 172M-E4 (later batch with 44rds ammo storage, all have skirts and smoke grenades) - called T-72M in our army
T-72M1 Obiekt 172M-E5(classic T-72M1, nothing to see here, move along) - called T-72M1 AS WELL AS T-72M by our army
T-72M4 (T-72M1 upgrade) - called T-72M4, no problem here, except army of course (see above) often stating it is modernisation of T-72M
Guess with T-62's and all other T's it's similar