What we consider to be a logo is actually a signature. The word logo was originally derived from logotype.
The Signature / Logo contains the mark and the logotype or either one. It represents the company or an individual.
Logotype
The company name.
The Logotype
Contains the word or words that determine the company.
Pictorial Mark
A pictorial mark is a recognizable image that has a literal meaning. It can appear with the name of the company or without.
Abstract Mark
An abstract mark is an abstract symbol. It can appear with the name of the company or without.
Monogram
A monogram uses one or more letters, often the initials of the name.
Emblem
An Emblem encases the name within the design
Trademark
Is a name or symbol that represents a company or product/service and is legally registered.
FedEx's Versatile Logo
The original name for FedEx was Federal Express it became FedEx in the early 1990s. By 1998 FedEx had acquired a variety of businesses.
Fed Ex's bold logo was now applied to all of the various branches of their business but at the same time each branch retained it's own individual identification.
When FedEx acquired Kinkos
they retained Kinkos' Mark and incorporated it into their own logo.