Wow! There is no comparison. They are two completely different communities.
Nellie Gail is mostly pretty old - think brick and oak galore, while Ladera is more like new and Tuscany.
Nellie Gail has HUGE lots, for the most part, while Ladera's are PUNY by comparison.
Nellie Gail has horse property, while Ladera is built around kids and cul-de-sacs.
Nellie Gail has a low tax base and low HOA fees, while Ladera has a combination of prohibitive taxes + Mello/Roos, and high HOA fees.
Nellie Gail some exposure to freeways/tollroads/power lines, while Ladera has some exposure to busy streets & power lines.
I suspect - but am not sure - that more of Ladera is offered as distressed proeperties, simply because most of Ladera was built in the early to mid portions of the 2000's, while Nellie Gail was established before 2000.
Those are just some of the differences that immediately come to mind.