Assuming you're talking about
groupinstall command installs a bundle of packages that are designated as a group so that you don't need to install a bunch of individual packages yourself to have all of the features. So
yum groupinstall "Engineering and Scientific" would install a bunch of packages that someone decided should be used on engineering and scientific workstations. Likewise
yum groupupdate "Engineering and Scientific" would upgrade those packages if necessary (and install any new ones) and
yum groupremove "Engineering and Scientific" would remove all of them.
yum grouplist will list the possible groups.
yum groupinfo groupname will show what packages are members of
groupname (you will need "quotes" if there are spaces in the group name).
More details here (grouplist and groupinfo) and here
The regular install just installs individual packages (and their dependencies) by name.
Personally, I think individual packages are the way to go unless you aren't sure what package you want, and want to try all of the Editors to see which one you like.