Two very different races. Here's every stat, side by side, to help you pick.
Indicative — based on GPX data. Both courses normalised to start at 0m.
✓ marks the better number on that stat.
Both are flat, fast European loops, though Berlin has the pedigree — a 2:01:09 course record and more men's world records than any course in history, against Rotterdam's smaller international profile and roughly 15,800 finishers. Rotterdam's elevation profile (86m of gain) is a touch hillier than Berlin's dead-flat 58m, but still well within PB-friendly territory.
Rotterdam's April date makes it a realistic spring alternative to Berlin's autumn slot, and it's markedly easier to get into — no ballot lottery standing between you and the start line the way Berlin's does. If the Majors-adjacent prestige and record-course history matter, Berlin is the pick; if you want a flat European course with a straightforward entry process, Rotterdam does the job well.