The 338's I would consider are, .338 win mag, 338 Rem Ultramag, .340 wby, I own the latter.

There's also the .330 Dakota, and many others I'm sure, but the above 3 I think are the most popular/available/around.

I think the .338 Lapua is very close to the speeds of the .338 RUM and .340 wby, though I believe its usually loaded with lighter bullets like 180gr or 210gr, which the RUM I think is only loaded with 250gr and most 338 guys use 225 or 250, handloaders can load 275gr! So the lapua with a 180 or 210 will be faster than a 340wby or 338rum is with 225 or 250 but comparing those weights I think the RUM and Wby are faster.

Are you looking to get one, or just wondering the differences?