There were just slight differences.
Wikipedia described the insect as follows," 'Spilomyia fusca ... is a fairly common species of syrphid fly ... The adults, also known as flower flies for they are commonly found around and on flowers from which they get both energy-giving nectar and protein rich pollen. "
Another Facebook user posted, "Fly=1 set of wings," as a tip for identification.
In fact, a post by Beatriz Moisset on the Hummingbird Moth (fs.fed.us), said, "They fly and move just like hummingbirds. Like them, they can remain suspended in the air in front of a flower while they unfurl their long tongues and insert them in flowers to sip their nectar."
Moisset went on to write, "there are several species of hummingbird moths. ... The most familiar ones are the Snowberry Clearwing (Hemaris diffinis) and the Hummingbird Clearwing (Hemaris thysbe). They are both widespread throughout North America ..."
Meanwhile, another insect that is often mistaken as another is the spicebush swallowtail.
It has a very similar appearance to that of the female dark form on the tiger swallowtail.
The difference is limited to some spots.
Again, I suspected that the difference was down to a couple of spots. I felt I might have to give in and download a couple of insect identification apps.
Of course, the lookalikes weren't limited to just the insect population. What I thought were some poisonous jack-o-lantern mushrooms, were not. (Oops... they were.)
The next day they had grown to reveal their true form as the edible chicken of the woods. (No, they hadn't. They were jack-o-lanterns.)
Is it a fly or bee, A bird or a moth, edible or not? Nature will always keep me guessing.
That's just the nature of things round here.