its the difference between quick and fast.
a 1/10 buggy will be very nimble and quick on a racetrack. however the 1/8 will be a total powerhouse. will out accelerate just about anything. and absolutely wilk out corner a 2wd buggy. regardless of the motor.
the 1/8 will be more durable as a beginner but more dangerous for everyone around you. the 1/10 WILL make you a better driver until you move up to the 1/8.