What is the difference between travel and travelling?

I would like to ask whether someone can explain the exact difference between 'travel' and 'travelling' to me. Some dictionaries say that travelling is an adjective but other dictionaries say that travelling could be a noun, too. I have not found any answers regarding my question yet, so it would be great if someone can help me here.

Traveling is the present participial of the infinitive verb to travel. Particpials may take the form of a noun (gerund), a verb, an adjective, or an adverb(ial phrase). At its core, it is still a verb. Although somebody on this site is going to disagree, here are a few examples:

Traveling is fun. As the subject, I would call traveling a gerund, and thus, a noun.

Are we traveling to Spain? This example shows traveling as the priciple verb to the auxiliary are.

They are gone, traveling to the moon. [T]raveling to the moon is an adverbial phrase; although traveling in and of itself is a verb.

The traveling circus is coming to town next month. Here, traveling is an adjective modifying circus.

American English spellings.