How do I differentiate between signals from an unknown program?
Just a few pointers, since a complete answer would be way too long.

The link you give for the key fob lists its FCC ID: CWTWB1U331. Using a search engine, you can find its entry in the FCC database: https://fccid.io/CWTWB1U331

The FCC database is a goldmine because it lists many of the operational parameters of the device. For example, you can verify that the frequency range you're looking at is correct.

Among other things, you can learn that the modulation is ASK, and that the line encoding is Rolling/Manchester. In particular, the "Test Report" pdf has a couple of extremely helpful figures, which will help you narrow down the transmitted frequency and the line encoding format.

For example, from Figure 2 in that document, it seems like there are 10 bits in 5 milliseconds, for a data rate of 2000 bits per second.

Another thing to note is that essentially all key fobs will transmit a different word every time the key is pressed, so the job of identifying the key will imply finding each key's patterns, which will not be easy -- otherwise, car theft would be a piece of cake.

Finally, there are several resources online for reverse-engineering wireless signals, such as remote controls and garage door openers. I recommend that you look for those.