we decide ___ spending vacation by the sea.为什么要填on?spend我为什么要加ing?

decide on doing sth.
decide to do sth.
决定做某事请问这两个有什么区别？可以互换么？谢谢可以互换的 都做“决定”讲 We decide on spending vacation by the sea.=We decide to spend vacation by the sea.