A way to tell the difference between ammonium nitrate and urea

Hello, so I joined this forum today, also started home chemistry as a hobby recently (However learning chemistry for 6 years now, as of today I am graduating, taking my exams next week). I really like to gain practical knowledge.

So, the first material I tried acquiring, was Ammonium nitrate from a cold pack that was left in my home and unused. The thing is that i dissolved it in water, filtered from anti cracking agent, and left for crystallization. So finally it crystallized. But I when I have read more about instant cold packs, I found out, that there are two types: made from Ammonium nitrate or Urea. So the question is, how should I know which material I managed to acquire? Is there a way to determine that? Thanks

P.S. Sorry for bad English.