EXL’s and NYXL’s have the same ball ends as far as I can tell - brass/red/black/green. I have a set of each on my basses right now and the ball ends are the same.
Quick test - does the bass seem to stay in tune for an unnaturally long time (like, days?) If so might be NYXL’s.
I tune them every two days (I use the DJ one day, then the GZ the next day, etc.), they stay in tune reasonably well, +/- 1 notch on the tuner at most.
My SR500E used to stay perfectly in tune for weeks with the factory EXLs though. (Until I put on these crappy discolouring Ibanez strings and tuned to D standard…)
As I’ve stated previously I have always been a flat wound fan but I am so glad I took a chance and followed the suggested string selection from the finder tool.
The EXL170 strings are fantastic and have given the Warwick a whole new range of tones over the flat wounds 
Those and the NYXL’s are definitely my favorite strings. Feel great, sound great.