if are the same?

Find out who makes the IC's and contact them.

74HC and 74LS (low-power Schottky) are sub-families of the same logic chip, just using slightly different technology. The two logic chips are comparable in function and similar in compatibility but do differ in some ways (such as input drive current, speed, bandwidth, etc).

Check and compare the data sheets for the two chips to ensure compatibility with your design.

I doubt they are the same. hc is probably high output power and ls is low power. Logically the same, but the fan outs and current draw are considerably different if this is the case. If you try to sub, going up in current (from ls to hc) is the only direction, but a lot of power connections to the chip may require better filtering to handle the additional switching spikes from the chip. You may also try a straight 74164, if you are subbing for the Ls. It's standard TTL and should be between these 2 chips in current capacity,if the Hc does stand for high power,like I suspect. If you're subbing for the HC, You might try to solder 2 74164's in the circuit by piggy backing them together, if you're desperate. The current capacity of the ls will be too low to try the same thing trying to sub an ls for anything else. If this causes you more questions, let me know.

Thanks Bill. Late last night I wondered if That C stood for Cmos. Thanks for setting me straight.