The keyword throws is a declaration "warning" that the associated method or class might throw the indicated exception(s). The keyword throw is used to actually throw something. For example...
In general, if an exception is caught, then it is considered handled and does not need to be declared with the keyword throws. For example...
"We're kind of on the level of crossword puzzle writers... And no one ever goes to them and gives them an award." ~Joe Strummer sscce.org