Just to add to this, a PEG tube usually has a mushroom shaped device on the end that holds it in the stomach and makes it very difficult to fall out. Most doctors prefer this style to allow for proper healing. Some doctors prefer to place a long PEG tube and some are now starting to place a PEG button, with the same mushroom shape but the extension tube can be removed. The button is more discrete and you don't have to worry about the long tubing when it's not in use. The tubing on the PEG button does not lock into place so if the patient pulls on it, it will easily come right off. It might cause a mess but it protects the stoma site while it's healing. The most common type of PEG button is the Bard button made by AMT. You can do a search on it to see pics.
After a couple of months the PEG tube or button is often removed and replaced with a balloon type button. The PEG tube/button must be pulled out by force and it's painful and scary but it only lasts a few seconds. Then the balloon type button is inserted. Intead of a mushroom, it has a balloon filled with water that can be easily removed and changed at home. The most common brand is Mic-key button. Another one is the AMT Mini Button. There are a few others but these are the most commonly used. The extension tube twists and locks into place to prevent messes during feedings. Very convenient!
The general term is G-tube or G-button and that can include PEG tubes and buttons. The "PEG" term is to specify that it was placed during a PEG procedure.
Hope that helps.
Darshani (not a nurse yet but mama to a gtube kid)