Clear the table = remove items from it. We clear the table at the end of a meal by removing the plates, cutlery, etc. If you were working at the table, and it had your laptop and some books on it, you need to clear the table (remove the laptop and books) so that people can sit down and eat. Clean the table = remove dirt from the table, usually using a wet cloth or sponge and some kind of detergent. (Wipe the table = remove dry, easy-to-remove debris, like breadcrumbs, by passing a cloth over the surface of the table.)

While the two terms can sometimes be used interchangeably in casual conversation, they technically have different meanings. "Cleaning the table" typically refers to the act of sanitizing it. This could involve wiping down the table with a cloth, using a disinfectant, or removing any stains or spots. The goal is to ensure the table is clean and hygienic. On the other hand, "clearing the table" generally refers to removing items from the table after a meal. This could involve taking off the dishes, cutlery, napkins, glasses, or any leftover food. The aim is essentially to make the table ready for its next use, which could be another meal or a different activity. Therefore, both actions involve making the table ready for further use, but through different procedures.

"Clearing the table" is idiomatic. It means taking away the used plates and glasses. "Cleaning" it only has a literal meaning.