Differences between alkyl halides and alkyl tosylates
Both can be leaving groups. In general, TsO- are better leaving groups, thats why they are often specifically used as so. Halides can be used in many more reactions, like preparation of organometallic compunds.
TsO- more common function is to transform an alcohol group in a good leaving group. Formation of an halide, usually is not the way to go in this case.

But their basic reactivity is very similar.
If you dive into more complex reactivity, you can complicate things to a very very large extent...