I believe the SC250 is pretty much identical to the discontinued Singlecut, except it has different pickups and an adjustable bridge as standard (to allow for downtuning).
The SC245 is basically a lot more vintage Les Paul-ish (since Gibson lost that court case!) - shorter scale, PAF-style pickups, slightly thinner headstock and Kluson-style tuners. It has the non-adjustable stoptail as standard.
They both have maple tops, thick mahogany bodies and wide-fat necks.
The SC245 seems to get slightly more praise in reviews, but then most reviewers are vintage LP freaks! I'd have thought a S/H Singlecut is better value for money if it's cheaper, but it depends what features you want.
(I must say I've never played either! :) )