I'm not asking about what a force does i.e. attract, repel, etc., so please don't give the standard physics definition. I'm asking what it is, and how it is different from matter.
A 'force' is just a convention.
When things happened, such as someone pushed a physics book across a table, some people were curious and believed it was necessary to quantify what was happening.
They devised a set of conventions such as mass, motion, and acceleration.
When an object wasn't moving, and then later was moving, they said that something had acted on it, and they called that something a 'force'.
Then they were able to relate these terms in mathematical equations, such as F=ma; this made it possible to predict what would happen in certain circumstances, so people knew that these conventions were useful.