Use the Compressor to “even out” the sound of your track. It can also glue a track together by reducing dynamic range and make your voice sound thicker and more powerful.

Use the Limiter to “place a cap” on the volume of your input.

These effects will be written to the file! So, if you plan on using compression or limiting later on in your DAW, you may not want to record with it on. Although there’s nothing wrong with compressing or limiting twice if you get the sound you want.