Colon (:) - A colon is a punctuation mark you will come across very often in different circumstances. It can introduce an example, a list, an explanation, or a quotation. Or, you can also use it to emphasize a certain point.
For example:
There are two things you can do: continue being miserable or move on with your life.
There’s only one person in the world who can tell you what you should do: you.
Semicolon (;) - A semicolon is a punctuation mark that creates a longer pause than a comma but a shorter pause than a full stop. So, it can be used to create a pause between two independent clauses that are still closely related to each other.
For example:
My mother is a doctor; my father is an accountant.
Jane has spent the whole morning trying to figure out what to wear; she ended up choosing the first outfit out of all that she tried on that day.