There are two major types of processors being used in home computers today. Macintosh computers are based on a family of CPUs created by Motorola. IBM compatibles are based on a family of CPUs made by Intel. These different CPU flavors have completely different sets of instructions that they read at the simplest level. A program written to run on a computer based on the Motorola CPU will not run on a computer that uses an Intel chip. Each of these families of processors has a number of models available. The latest processor is almost always much faster than its predecessors, and more expensive. In the Intel world, for example, we have had the 8086, the 80286, the 80386, the 80486, and the 80586. Computer sales types refer to these processors as: 8086, '286, '386, '486, and Pentium processors)
Each of these processors has been roughly twice the speed of its immediate predecessor.