Control
electric speed controllers
2.4ghz radio
Performance
high capacity batteries
lipo batteries
brushless motors
Nitro
nitro electric starts kinda handy
Better fuels
Build quality
Manufacturers putting way more R&D into their products and using much stronger materials
Old-skool RC'in used to be SO frustrating!
Kids today will never know the struggle of:
MSCs getting stuck or go out of configuration so would either fly off and crash or not move.
27mhz radio gear that suddenly decides to not work when your car is full pelt due to random interference so it flys off and crashes.
Rubbish low capacity Nimh and Nickel batteries that lasted no time at all and took ages to charge.
Not very good glow fuel that was pretty hard to get engines running on and seemingly never consistent.
The cars broke, like allot. Your RC time was always cut very short because your naff battery had died in 5-10 mins use or the car broke, either through failure of a poor part or more likely your car ran off and hit something hard at full pelt and destroyed half its self, and that would happen basically every time you used the car! with a nice expensive rip to the LHS and then a load of time repairing it. Rinse and Repeat.
Man I don't miss any of that!
The modern performance of a lipo battery and brushless motor in a well built strong, reliable, controllable car is what RC'in always dreamed to be.
I still find it novel to go out and run one of my cars and get to run until I have finished playing a