When I fly a ILS approach on the PMDG 737 vs FBW A320 the PMDG appears much higher with a faster decent… is this just me or does the 737 decend much faster than the A320 or is it just the sim tricking my eye

Probably the sim tricking your eye. The glideslope doesn't change based on the aircraft. As long as you've got two red/two white you're on the proper glideslope.  You could check to see if maybe you have 1 red/3 white in the PMDG which would indicate that you are indeed higher than in the A320 (assuming you have 2&2 there).

 

Maybe the pitch angles of the 737 and A320 are different on final approach?

A couple of things would give you that impression. One is the approach pitch and speeds involved. The 737 has a flatter approach than the 320. We are talking 2.5 to 3.5 vs 3.5 to 4.5 on approach for pitch. The 737s approach pitch will give you high/diving towards the runway feel and the 320 may give you the low lightly sinking feel. This is why you stay on glide path and speed on the approach regardless of the aircraft. Now, for a specific aircraft, like a DC10, I would get suspicious if I'm on a 3 degree slope and see something other than a 4.5 pitch with flaps 35. Now, lets talk real world for a sec.

Different airports may have different slopes depending on the needs. Mountains, obstructions, noise, etc will drive those. This will also change your approach pitch. You have have to identify that during the approach brief so that everyone knows to expect a different approach pitch than normal.

Speed can change that too. On approach, you can expect 1 degree of pitch change for every 5 knots of speed. All of these come together for a specific aircraft to form your landing picture. It's a good way to tell when something is off on approach.

 

Which 737?  Cause the -800 or larger are pretty much the fastest in terms of V-speeds on approach for their class.   The MD-11 was also a very fast approaching jet.  The 737-800/900 can easily be running 155 knots on final, whereas the A320 might be at 135.

Also  for the same glideslope:

faster approach speed = higher descent rate in fpm