Vintage Synth Repair

Hi, just out of curiosity, are the TC40HXXX ICs directly compatible with the 74LSXXX chips?  When i search for the description of any TC chip and match a 74LS of the same last three numbers they both seem to do the same thing/same description.  

Still trying to narrow down my issue with my jp6 and it seems the Tc40h chips in it aren't available anywhere.  Hope if i need to i can swap to the LS series

thanks
Greg