Return and profit
Return is what your money made, as a share of what you put in. €100 that becomes €110 returned 10%.
Profit or return
Profit is the amount: €10. Return is the rate: 10%. €10 on €100 is a lot; €10 on €10,000 is very little. Comparing rates is fairer than comparing amounts.
On paper or in your hand
While you still hold something, its gain is only on paper: the price can change tomorrow. Once you sell, the gain is real. Paper gains are called unrealised, real ones realised.
Total return
An investment can pay you in two ways: its price goes up, and it pays you cash along the way (like a dividend). Total return counts both.
Per year
To compare investments held for different lengths of time, turn the return into a yearly speed. 20% in total over 4 years is about 4.7% a year.
What you keep
The return you keep is smaller than the headline: fees, tax and rising prices all take a slice.