Manfrotto 054-Q2 (MH054M0-Q2) vs 055-Q2 (MH055M0-Q2)

Hi all, I'm looking at these two Manfrotto ballheads and other than the price, weight, size and load, they appear to be the same.  or could there be another difference between the two that their site doesn't specify?  for the 055-Q2 head, their site shows that it has a seperate ball friction knob, but it doesn't specify this for the 054-Q2 model.  but i'm thinking it has it but the site just doesn't say it for some reason.

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http://500px.com/baneling
Canon T3i
Canon EF-S 18-55mm f/3.5-5.6 IS
Canon EF-S 55-250mm f/4-5.6 IS