Generally, the higher the amount of saw blade teeth, the better the quality of cut and finishing. If you’re looking for a faster and rougher cut, then a blade with fewer teeth will be more suitable.
For example, if you are cutting aluminium or a high quality finish when cutting laminate, you will want a higher number of teeth compared to blades for soft wood.
When blades have fewer teeth, they have deeper gullets (space in between teeth) which creates a more aggressive chiselling action.