The only difference between the two is that the 2032 is slightly thicker than the 2025 -- either will fit and work.  The 2032 will last slightly longer.  
Hi: Dell XPS L502X Service Manual does not specify what type of CMOS coin battery. I want to replace mine. Can anyone who has opened their case please tell me the type/number of battery? I'd like to buy the replacement battery before I open the case.
XPS 15 L502X: CMOS coin cell battery - what battery type?