Apportion and portion are related, but they do different jobs in a sentence.
Apportion is a verb. It means to divide something and assign shares to different people, groups, or uses. You use it when the focus is on the act of distributing.
Example: The city will apportion the budget across several departments.
Portion is usually a noun. It means a part, share, or amount of something. It often refers to food, but it can also mean a share of money, work, or responsibility.
Example: Each student received a portion of the supplies.
A simple way to remember the difference is this:
- Apportion = the action of dividing and assigning.
- Portion = the part that someone gets.
If you are talking about what someone does with the whole, choose apportion. If you are naming the share itself, choose portion.