The CD4012 is a CMOS technology based, 4-input NAND gate Dual package, i.e. the IC has two NAND gates which can operate independently and each gate can take in four Inputs. It is commonly used in buffer circuits, logic inverter circuits etc.
74LS08 IC is a member of 74XXYY IC series. There are four AND gates in the chip and each gate have two inputs, hence the name QUADRUPLE 2- INPUT AND GATE. The gates in the chip are designed by SCHOTTKY TRANSISTORS for high speed logic operations.
74LS02 is a LOGIC GATE IC and member of 74XXYY IC series which are logic gates. There are four NOR gates in the IC and each gate has two inputs, hence the name QUADRUPLE TWO INPUT NOR GATE. The gates in the chip are designed by low power SCHOTTKY TRANSISTORS.