They are not very similar. Chorus is a "modulation" effect that changes the way your notes sound. Just search for chorus pedals on YouTube if you want examples. Boost pedals are generally used to simply increase your volume, although many can also lower your volume or alter your tone in different -- but typically subtle -- ways, either via EQ or gain/overdrive.
However, any chorus pedal with a volume knob could also be used as a volume boost as well, although not many of them could do so without also adding a noticeable chorus effect. The Iron Ether Polytope is one pedal that can be used to obtain both chorus and boost functions fairly well.