表示上车get onto 进入到…上面，he got onto the bus.他上了公交车。get into 强调里面。get onto表示在一个较大空间如 bus里get into 经常是在一个小的空间如car

get into 有进入陷入，养成等更深入意义。如He was eager to get into politics. 他渴望进入政治圈。还有隐身意义对…有兴趣如，he'd get into about a girl.