I don't have either machine - but saw a few listings, very cheap. I like these vsm's, but to date have researched only Singers - because it is easy to find information on those (as well as replacement parts and the like).
I have a Singer 15-91. Would like to have a treadle someday. Would like to have another machine as back up to my 15-91 - which I have now made my primary sewing machine. I just like the way these machines sew, and the fact that they are built to last and not to be a throw-away.
These White machines looked nice; the 2nd one I can see the belt on it - and I know that belted machines are supposed to be easily convertible to hand-crank or treadle.
I will google White 77. The info provided with that machine - I did google - but didn't come up with much - so I think the wrong info was listed.