Nowhere near the same.
When you fart, you are pushing the gas out a small hole. Not a lot of pressure, maybe 1psi depending on dinner bean content, but its concentrated and 100% of the force is behind 100% of the gas. Pressure pushes it through, you know it makes it through the fabric b/c you can smell it.
On the inhaling side though, the gas is already dissipated into the air. You're pulling vacuum through your nose, but that vacuum is immediately diminished and spread around a large surface area of the underside of the mask. The vacuum on the outside of the mask at any single point is very small, and is pulling in mostly air from everywhere and only a tiny bit of fart. Plus on top of that you have the filtering effect of the mask to stop of the fart particles from coming in.
Related - this is an educational article I found when looking for what the average pressure of a fart is.
The physics of a fart