There are several species, identification to some extent depends on where you are. If you are interested in IDying your local birds the best course is to buy yourself a bird identification guide, national guides are available for most countries and in the US there are individual guides for many states. Reasonable quality bird guides can often be found much more cheaply in second hand book stores.

Thank you so much such informative story.
Recently, we saw several black headed night herons on a small lake in Golden Gate park, San Francisco.

There are also at least two juvenals, but it is hard to be sure (for me) they are the same species.. Do juvenals have grey/whitish legs, while adults have yellow legs?

You have a beautiful photo of striated heron. What are other small brown and white herons?

Best,
Jacob