A1 The only difference is the scale. The names IC and LSI do not express differences in function or performance. IC stands for Integrated Circuit, and LSI, for Large Scale Integrated circuit. In the 1970s when ICs increasingly became large in scale, classification such as into SSI (Small Scale Integrated circuit), MSI (Medium Scale Integrated circuit), LSI, VLSI (Very Large Scale Integrated circuit), and ULSI (Ultra Large Scale Integrated circuit) was used. But expression could no longer catch up with a progress in integration. Today, therefore, the name IC is generally used and especially only IC that integrates more than several 1000 transistors is called LSI. A single transistor or diode that is not integrated is called a discrete component.