These terms are well defined and it would serve you well to simply consult a dictionary.
But in short colonialism implies the use of colonies (surprise surprise) meaning the use of settlers to control or displace populations. There from comes the name
It also differs from other forms of expansionism in a few important ways.
- The power class structure is built on trade imbalances which move resources from the colonised land to the metropole without building up local economies.
- There's no absorption, the territories tend to remain separate and the colonised people can't become citizens or equals with those colonising them.
- And it's understood when speaking about things like the "colonial era" or "historical colonialism" that there was a deal of racial justification and stratification along racial lines.
You'll quickly be able to compare this list to whatever historical event you like.