You can tell whether your I-140 is Eb2 or Eb3 from your I-140 approval notice (not I-140 receipt):
your I-140 is Eb2 if you find somehting on your I-140 approval notice as follows:
Section: Mem of Profession w/Adv Deg or Exceptional Ability Sec 203 (b)(2)
and your I-140 is Eb3 if you find something as follows:
Section :Skilled Worker or Professional Sec.203(b)(3)(A)(i) or (ii)