The way I think of it, a 'snapshot' is a picture that I take for a very specific reason but I don't really care how 'artistic' the image is. When I'm on vacation, for example, and I see a funny sign or a cute cat, or someone I'm with is doing something silly...I take the image for the sake of keeping that memory but not because there's anything particularly special about the image itself.
I think the reason why your shots were described as 'snap-shotty' is because there's not enough about the image itself that would speak to anyone else. The first shot is a flower. It's a pretty flower. So what was so special about it that made it important enough to photograph it? Was it particularly colorful? Was there a really interesting ray of light hitting it? Why did it stand out? You might have these answers in your memory, but none of that translates into the picture. There's nothing that makes it interesting enough - visually speaking - to any of us who weren't there with you. It feels like 'just a snapshot' of a flower - taken without a lot of thought into how the photo itself would turn out, but with the intention of just remembering that you saw a pretty flower.
But at least the flower and the trees (I assume it's not supposed to be sideways?) have clear subjects. The pictures of the trees is stronger because it's much easier to see what was interesting enough to take a picture: nice sky with some fluffy clouds, some pretty light hitting the tops of the trees, perfectly still water that created an interesting reflection of the trees. Both are pictures that could be stronger with more attention to placement, lighting, effects, but I can still sort of get why you would take them.
The third and fourth pictures, though...what are they pictures of? What am I supposed to pay attention to? The subjects aren't clear - there's nothing in either picture that stands out.
Someone else might have a different definition of 'snapshot', but that's just my 2 cents.
