What's the difference between chip families
74LS is Low-power Schottky - the output High level may be as low as 2.4 volts whne Vcc is 5 volts
74HC is High-speed CMOS - its inputs expect a High level to be above 2.5 volts when Vcc is 5 volts
74HCT is TTL=compatible High-speed CMOS.  Its inputs have a lower threshold for a High, to be compatible with 74LS outputs.
This information can be found in the datasheets for the various families.