I have a much longer version of this "Difference between Omni and Directional" antenna post. .It involves a necklace. But here is a shorter versio
Imagine you are in the nosebleed seats at the live performance theater (Been there.. Webber's Phantom of the Opera. Good show)
YOu can easily see the entire stage.. but from that far away.. ANTS
So you break out a set of OPERA glasses (Low power folding binoculars) now from that far you still see the stage but not the wings. and the people are at least PEOPLE.. but still small.
So you break out a set of FIELD glasses (Much higher power binoculars) now you can only see part of the stage.. But You can actually See the faces of the actors and actresses.
Same with antennas.
Omni. Just your eyes
Opera: Jack
Field: Sensar with Wingman