Resistance on one pole from mains
If you were measuring between a hot lead and neutral, with the power off, what you were seeing was the cumulative resistance of all connected (and switched on) loads on that leg. If everything was disconnected or turned off, you’d see infinite resistance.

What you probably saw was a very small load on one leg and a larger load on the other. Nothing to worry about.

BTW, I’m glad that you were smart enough to do this testing with the main breaker off. I still need to say this: never, ever do resistance testing on a hot circuit, especially at mains voltage! Ohmeters are designed to be used on unpowered circuits. Connecting a meter set to resistance to 120 volts could have caused the meter to literally blow up in your face, causing serious injuries or even death!