In lesson 3.6 the sentence "Bullet trains are faster than cars" and "Bullet trains are fast" both use 速い for はやい.
Another book I used taught me that the kanji for はやい (fast) is 早い .
When I use Google translate, 新幹線は車より速いです and 新幹線は車より早いです both translate to exactly the same thing - The bullet train is faster than a car.

Is there any difference between the meaning or usage of these two Kanji?

速い is used more often for speed, while 早い is used more for time. However, they basically mean the same thing and are used interchangeably.

Hi everyone!

As Nickさん said,「速い」is used to mean "fast" in terms of speed and quickness, while「早い」is used to mean "fast" in terms of something being early or soon.

They both have very similar meanings, but have a slight nuance to how each is different. It also doesn't help that, for quite a few sentences, either can be used and still make sense, but it would have a slightly different meaning.

E.g.
1.「新幹線は車より速いです。」vs
2.「新幹線は車より早いです。」

While they both generally translate to "The bullet train is faster than the car", the sentence with「早い」could potentially also mean, "The bullet train was earlier than the car", depending on the context. It could be that you were waiting to see which arrived earlier, and would just take whichever came first.

I hope this helps, and please do not hesitate to ask if you have any other questions.
がんばって　ください！

Crystal

Nickさん and Crystalさん , thank you for your replies. I now understand the difference which, now I know, makes a lot of sense and is easy to remember.

Mike