Yes, the difference between the two is prinicpally weight and muzzle velocity.
In its history, the .50 BMG caliber has trended to lighter and lighter weight bullets, which yielded faster and faster velocities. Faster velocities were desired as, up to the Korean War, the .50 caliber was the principal caliber for aircraft. As aircraft got faster and more maneuverable, hitting one with a bullet launched from another aircraft became more difficult, requirng shorter “times of flight.” Eventually the BMG was just replaced by 20mm cannon.
The actual trigger for the change in bullet designs was the role of “Ball” ammo in this caliber. Ball and Tracer are the training rounds, and needed to be a ballistic match to the tactical round. Prior to the M33 Ball, M2 Ball was the standard as it was a ballistic match to the tactical M2 Armor Piercing round. M2 AP wasn’t made after WW2 in the US, being replaced by M8 API. So, with M8 API being the tactical round, the M2 Ball was no longer a match. That necessitated the creation of a new Ball round, the M33.
First lots of the M33 Ball in the US were manufactured in 1951, with last lots of M2 Ball being produced in 1950.
Besides weight between M2 & M33 Ball, the M2 Ball has an exposed steel core at the base, with a lead point filler inside the copper jacket. The M33 Ball has a base plug of lead covering the mild steel core, with an inert point filler material inside the copper jacket.
All the .50 Ball rounds are mild steel core, not lead, since the first “production” models in the 1920’s.
Fifty Caliber Shooters’ Assn.