Complex sentence: The term climbing is used for the activity of tackling the more technically difficult ways of getting up hills involving rock climbing while "hillwalking" refers to the easier routes, but some summits require climbing skills, and many hillwalkers become proficient in scrambling.
Split into simpler sentences: The term climbing is used for the activity of tackling the more technically difficult ways of getting up hills involving rock climbing while "hillwalking" refers to the easier routes. Some summits require climbing skills, and many hillwalkers will become proficient in scrambling.