Assuming you're talking about woodworking:
There is no easy answer when it comes to choosing between a sander and a planer. It really depends on the project you're working on and what kind of finish you're hoping to achieve. If you're looking for a smooth, finished surface, then a sander will probably be your best bet. On the other hand, if you're trying to remove excess material or level off an uneven surface, then a planer might be more appropriate.
Here are some things to keep in mind when making your decision:
-The type of wood you're working with: Some woods are more difficult to sand than others, so if you're working with a particularly hard or soft wood, that could sway your decision.
-The size of the project: A large project is going to take considerably more time to sand than a small one. If time is a factor, then that's something to consider.
-Your budget: Sanders and planers can vary widely in price, so if cost is an issue, that's another thing to think about.
-The level of detail required: If your project requires intricate work or very precise measurements, then a planer might not be the best choice since it can be difficult to control how much material is removed at once.
Ultimately, there is no right or wrong answer when it comes to choosing between a sander and planer - it all depends on the specifics of your project. Consider all of the factors above before making your decision and go with whatever tool will help you get the job done right.