compare two netlists

Hi, 

I need to compare two netlists frequently, one is old netlist, one is new netlist. Suppose only several updates have been done in the design, meaning 99% of netlists should be the same.

But when i compare two netlists by tkdiff command, i find many cells sequence is changed, although the content is the same. As designer it is quite annoying to locate the difference between two netlists. 

So I wanna to understand the rule of netlist creation, and is there anyway to force spectre netlist not changing cells sequence?

Or virtuoso has any other way to compare two design efficiently?

BR