Computers are faster. Computers use less electricity. Mass production makes computers less expensive. Timesharing allows users at different terminals to work with the same mainframe at the same time. The most powerful mainframes are called supercomputers.
Minicomputers are smaller than mainframes, but larger than personal computes.
Personal computers are low-cost, typewriter size computers. Today's personal computers are as powerful as mainframes were before. Now PC's are everyday tools in offices, factories, homes and schools. Powerful desktop workstations do many of the jobs formerly done by minicomputer and mainframes. High-end personal computers are approaching the power of many workstations.