For example, what can a bat do that a bird can’t? Or a bug? Or isn’t there one and they all kinda got to the same place by diffirent routes?
This is a pretty big question. Bats are highly maneuverable and can catch individual insects in flight. Vultures can soar like a sailplane with minimal effort on their part. Hummingbirds have small wings that beat many times a second. They can hover. Flying squirrels and flying fish can’t truly fly but they can sail to help them in their niche. Wing design is extremely important to a given species.
The very large differences in wing structure between bats, birds, and insects basically are due to differences that were found in the ancestors of these groups. These differences did not evolve due to the advantage of one of these basic designs over the others. However, these designs place limitations on the flight capabilities of each group.
Insects are obviously different. Their chitinous wings would not work at larger scales. Because of their size, insects can do some things that birds and bats cannot, and likewise cannot do some things that birds and bats can. But this is a matter more of size than of structure.
Bats cannot do some things that birds can, but it is uncertain whether this is due to limitations in the structure of their wings, or simply because they are less diverse than birds. Bats do not soar for any distance. Bats cannot perform the acrobatics that hummingbirds can (although some can hover). It is possible that bats have not evolved into some niches because birds already occupy them. If there were no birds, bats might be much more diverse.
Wings are an example of convergent evolution; that is to say, several different classes or orders of animals independently developed wing or wing-like structures for flying. The question is really too general to answer, but as one example, save for hummingbirds (family Trochilidae) birds can’t hover the way many flying insects do. Conversely, most insects can’t really glide the way many birds can (hence the old saw about how a bumblebee can’t fly).
Each wing structure has a particular advantage to its family or order of beholder in accordance with how it lets the animal be more effective in its peculiar niche. To say more would require a specific wing structure/species to discuss.
Stranger
Here’s a recent article about an intricate study on bat flight done at Brown University.
A bit from that article:
On the same Science Daily page (scroll down the sidebar) there are two other articles on similar studies with hummingbird and bee flight. New technology, high speed digital imaging, has been key in these studies. Pretty exciting stuff, not only for understanding Nature, but it will also lead to new developments in human flight.
I’d quailfy that.
It is very difficult to observe bats in the wild at night, & making broad statements about what they can & can’t do seems unreasonably hasty.