Relative definitely. But let me clarify that, when people talk about 'relative strength' they are usually betraying a bias which favours the smaller lifter. For me it isn't about using 'relative strength' as a justification to favour the lighter lifter but as a means to assess what I think is impressive based on bodyweight and what others are doing with similar body weights.
To me Lamar Gants close to 700lbs pull is just as impressive as KK's 900+. They're both just bull strong.