In whare atoms in group 1 and atoms in group 18 different?

metals

nonmetals

noble gases

metalloids

Group 1 contains metals while group 18 contains noble gases.

So group 1 is different from group 18 as they both contains different types of atoms as group 1 contains metals while group 18 contains noble gases.

There is 1 valence shell electron in group 1, they are highly reactive while valence shell of group 18 is fully filled and they are least reactive.