At early Level, What im hearing is that because the sound is compressed, the transient sound feel quieter, and even change slightly its tone to a lower note ( mind trick ), so i usually based myself on the Kick Drum or Snare Drum ( mainly ) so you can hear it correctly.

if it happens that the two Snare or kick from each signal are at the exact same level it means that they added the output level now, to which means that now, on the compressed signal, the quieter part is more prominent.
So in this case, if the two transient sound on each signal are a the same level, the one that has the more tail sound is the compressed sound.

Try this, this has been working like a charm so far

Each sample play typically consists of two sounds. In the earlier levels, the compression ratio tends to be quite high, making it easier to compare the dynamic range. Dynamic range refers to the difference in volume between, for example, the drum and the shaker. If the shaker is very quiet and the drum is loud in the first take, it’s likely that in the second take, the drum will be slightly quieter and the shaker slightly louder, resulting in a reduced dynamic range aka more compression.

I might suggest that the punchier sound is less compressed - though this isn’t really technically accurate at all, it might help guide you in the right direction during the initial levels.
I personally struggled with this game until I learned more about compression. Without an understanding of compression, you might notice differences in the sounds but find it difficult to identify which one is more compressed. Probably best would be to find a tutorial and play with a compressor in your DAW - just to understand what it does.

Maybe that helps a little bit.

I struggle with this one as well. I went to YouTube and watched 4-5 videos on How to Hear Compression and it REALLY helped. The House of Kush had a great one.

In comparison where the ratio is the same or close I hear different Attack values as tighter for higher Attack and Looser/washier for lower Attack. Ex at an 8:1 ratio a loop with a 10ms Attack value will have a much more open/looser sound than the loop at 25ms. Also check out the Compressor video on Mastering.com. It is free and well worth the time.

Don't worry most people have the same problem as you, try to see it all

It does take a good amount of time to hear and understand compression. Idk if this helps, but try to isolate the different instruments you hear in ur head. So let's say you hear a kick, snare, and percussion all at once. Try just listening to the kick for example and compare them and then so on. Does it sound softer,quieter,punchier, or more groovy in the other comparison? There's a good chance if the individual instrument is softer or quieter,etc...it has more compression. You'll also hear overcompression if it is sounding a bit squashed down and kinda dead. As you get more advanced you'll automatically hear it without isolation. I hope this helps some.

Thank you all!

Guys I just got to 12/12 on level 1! I'm actually glad I didn't beat level 1 because I still don't think I'm ready to go to a higher difficulty. I thought the point of a Compressor WAS to stifle and suffocate the sound of the drums to get them out of the way for the other instruments??? Maybe I am confusing Sidechaining a Kick to other tracks and why a compressor is need in that context... But on this game the more compressed sound signals sound more airy and lush?? Isn't the point of a compressor to chop off peaks (transients) and capture the sound so that it doesn't sound too loud and large??
... Actually, now that I reviewed your comment, you said does the signal sound more groovy, quieter, punchier, etc, so now I'm realizing what I may need to be listening for is if the signal has been altered in some way to make it sound more enhanced or Interesting or something, just not a raw drum signal. GEEEZ thank you SO much for helping assist me in actually identifying this compressor stuff!!!

10 hours!