The Transform Command
Transforming scales, rotates, skews, stretches, or warps an image. You can apply transformations to a selection, an entire layer, multiple layers, or a layer mask. You can also apply transformations to a path, a vector shape, a vector mask, a selection border, or an alpha channel. Transforming does affect image quality when you manipulate the pixels.
The Transform Selection Command
The Transform Command transforms pixels. There are times when you just want to transform a Selection and not the pixels.
Ten you need the Transform Selection Command. Its a little bit hidden away but once you find it you will be a friend for life