Fiber optic is a specific kind of cable used for different kinds of telecommunications, while T1 denotes a carrier system or signaling scheme, which is not limited to one specific kind of cable, but is often defined by the speed it is capable of. Fiber optic cables can carry the T1 signaling scheme, but the two differ in many ways, and have little in common.
When considering different telecommunications hardware and carrier schemes, the most important metric of comparison is speed. T1 lines are defined by their speed, which is, optimally, around 1.544 megabits per second of data transmission and reception. Fiber optics, on the other hand, are capable of significantly faster speeds, and researchers have used fiber optic cabling along with other hardware to send data at speeds over 100 Petabit/s, which is the equivalent of 100 million Gigabits/s.
Fiber optic cables work by sending light between the two ends of the fiber optic cable. Silica and other glass-like materials are used to form the core of the cable, which is responsible for transmitting the light, and this inner material is surrounded by cladding, the purpose of which is to contain the signal to the glass-like core. T1, because it is a signaling scheme, does not have any physical properties. It can be used on many different kinds of cables, including fiber optics.
The T1 signaling scheme is a very popular form of telecommunications with a number of different applications, including both Internet and telephone lines. Fiber optic has many different uses, but with regards to telecommunications it is usually used as a backbone cable because of the high speeds it is capable of and because the signal degrades much slower than on electronic cables. Therefore it is ideal for use over long distances, such as trans-ocean cabling.
As technologies improve and bandwidth increases, and because the T1 signaling scheme is limited to a certain bandwidth, it will probably be used less and less, especially for data applications. Fiber optic cables, though, are capable of extremely high speeds, and are destined to become more popular because of this. In March of 2011, Google declared Kansas City the winner of a contest to wire an entire city with fiber optic cable. The project is thought to be, in part, a way to spur ISPs to begin connecting customers via fiber optic cable.