Will a 6ft bed liner on a 1995 Ford Ranger XLT, work on a 2002 Ford Ranger with a 6ft box?

 

Yes, if both are style side(regular side) or both are flare side(step side)

1993-2011 Rangers all used same 6ft bed, extended or regular cab
There were Long bed regular cabs with 7ft beds

 

Will a 6ft bed liner on a 1995 Ford Ranger XLT, work on a 2001 stepside??

 

No, not unless BOTH are stepsides

All Rangers have the same 6ft bed, regular or supercab, there were a few "long bed" regular cab Rangers using 7ft beds, and no they will NOT fit on 6ft bed Ranger
1983 to 1992 beds are 2" narrower than 1993-2011

Then there were two 6ft bed styles, regular and stepside, stepside bed AND tailgate are narrower that regular bed, no stepside long beds

And Ford actuality uses Styleside & Flareside, for regular and "stepside"
GM trucks use Fleetside & Stepside