These Ukrainian fighters are stored at Luts'k airforce base which is now used as an aircraft storage base. They are probably MiG-23's or Su-24s, whith those retractable wings and the extra fueltanks still under them. As Su-24s appears in most pictures I've seen whith a grey colour i think these are Su-24s.
btw Can anyone tell me the difference between a MiG and a Su?

Those are Su-24s. You can tell by measuring them for one.

Size is different as mentioned by SOC. But the 'Fencer' has a broader fuselage as well because it's a two-seater ground-attack plane with side-by-side seating.
'Fencer';


'Flogger';

There's also a two-seater version of the MiG-23 'Flogger'. It's the trainer version but it has tandem seating.