What is the difference between a variable expense and a fixed expense?

In a Fixed Expense there is no change in the price. Examples of fixed expenses are things such as Rent, Car payments, dues and insurance (just to name a few of the top of my head).

In a Variable Expense, things are subject to change over time, they change based on circumstances. Examples of Variable Expenses are, gas prices, groceries, electrical bills, and services that charge based on work completed.

Short Answer: (Summary)

So to summarize, Fixed Expenses stay the same, Variable Expenses are likely to change.

Explanation:

So let's think about the concept between the two terms, Fixed Expense and Variable Expense. In a fixed anything there is no change, as opposed to variables which are subject to changes based on the situation, (they adapt I guess).