What is the difference between "gleich", "gerade", and "nur"?
So far, I know that "gleich" is "just" or "directly", and "nur" is "only". I'm not sure what the difference between "gerade" and these two is.

Question

What is the difference between "gleich", "gerade", and "nur"?
So far, I know that "gleich" is "just" or "directly", and "nur" is "only".  I'm not sure what the difference between "gerade" and these two is.

Answer

As you already said "gleich" can mean just.
"Das Haus ist gleich um die Ecke" = The house is just round the corner.
But it can also mean "equal, similar".
"Die Häuser sehen gleich aus" = The houses look similar.

"Gerade" can mean "just" too but in a different way
"Ich kam gerade nach Hause" = I just came home
But "gerade" can also mean "even, straight".
"Eine gerade Linie" = "A straight line"

And "nur" is just "only, merely"