Travel: a journey especially to a distant or unfamiliar place.
Explore: Explore something is to travel through an unfamiliar area in order to learn about it or else to examine something.
Discover: Discover is to find something or else to gain knowledge or become aware of something.
travel - путешествие в далекое или незнакомое место.
Explore - тур с целью исследования
Discover - открыть что-то новое.
Примеры:
Radium was discovered by Marie Curie.
The biologists were excited to explore the new land as they hoped to benefit from this journey.
I want to meet a person who has traveled the whole world.
Объяснение:
Interesting, - more interesting - the most interesting
Much -more-most