We visited the gardens recently and observed several small flying creatures that looked like bees but flew like a hummingbird. What did we see ?

Hummingbird moth is the common name used for the genus Hemaris, which include: Hummingbird Hawk-Moth, Sphinx moth, Common Clearwing Hummingbird moth, Snowberry Clearwing Hummingbird moth, Five-Spotted Hawkmoth, and White-Lined Sphinx are all names for the hummingbird moth that you described. Google it. They are a fascinating little moth.

Not sure but they do have hummingbirds on the property, to my knowledge. You could easily see both.