Think of it this way:
* Perm: Reconstructs the entire structure of the hair to create a new curl pattern.
* Texturizer: Loosens the existing hair structure and enhances its natural wave or curl, if any exists.
If you have very straight hair and want curls, you'll need a perm (also known as a "body wave" for looser curls). A texturizer will likely only add some body and slight wave, but not defined curls.