For people who are just learning to speak the English language, it sure is very confusing at times. Here are some of the commonly confused words that will at least give you a bit of clearance.

Especially = particularly
Specially = for a purpose

Farther = about distance
Further = about the degree

Older = comparing ages of people
Elder = comparing ages of family members

Altogether = completely, in total
All together = all in one place

Beside = next to
Besides = in addition to