?What is the difference between move between lines and varying position?

[QSF25]

What would the player do physically in the pitch?

[THOG]

Are there specific TIs you have in mind?

"Moving between the lines" would generally mean a player on the attacking team positioning himself in space between the lines of the defending side's formation to receive the ball. For example, a midfielder moving forward into space between the opposition's central midfielder and central defender. Another example would be a forward moving back into the same area.

"Varying/changing position" would generally mean an attacking player temporarily swapping positional responsibilities with a teammate. For example, a winger moving into the middle to act as the striker whilst the striker moves out wide. This is usually done to force defenders to switch who they're marking and give creative attacking players more opportunities to receive the ball.

Moving between the lines could involve changing position and vice versa, but not necessarily.