The goal of the Magnuson-Moss Warranty Act of 1975 was to protect consumers against "sketchy" warranty practices. The act requires warranties to be worded in a very specific way so that consumers have a better chance of understanding them.
Your question relates specifically to the differences between implied, express, full, and limited warranties, so that's what I'll talk about.
- Implied Warranty = This is the least "warranty" like of the four. It's a warranty, essentially, against scams. It has a few important components for "real" products: fitness for purpose says that, for example, you're protected if I sell you a hammer made of plaster of Paris because it would never work for its specific purpose (hammering things.) Merchantibility means that the product must actually contain the things on the label, be labeled for sale, and that if 10 of them are for sale all 10 should be made with the same quality. Habitability is the idea that if you sell me a house, it must be suitable to be lived in (unless otherwise noted.)
- Express Warranty = These are promises made about a product. If you buy a blender that the box says will also cook toast, and it doesn't, you're covered. This does not apply to product "puffery," where a manufacturer claims their product is "great." Just because you don't think it's great, you don't have a complaint under an express warranty.
- Full Warranty = During the time agreed to, any manufacturing defect found in the product will be repaired, or the product will be replaced.
- Limited Warranty = Similar to a full warranty, but restrictions apply. A limited warranty might cover the motor on something but not the case. Limited warranties are often used to cover the product parts but not the labor, or vice-versa.