We joke about England and the United States being just "across the pond" from each other, but a real pond is nothing like the ocean that separates these two countries. And while both lakes and ponds are inland bodies of freshwater that contain living organisms, the website for the Lilly Center for Lakes & Streams at Grace College in Winona Lake, Indiana, says the primary differences are in the depth and surface area of each, and therefore the resulting biomes of each.
Ponds are generally the smaller and shallower of the two, resulting in less surface area. They're considered lentic systems, which means they're pretty much bodies of standing water. That water also is in the photic zone, meaning it's shallow enough so sunlight reaches the bottom. The light allows plants to grow at the bottom, too, as well as on the surface. The water in a pond tends to maintain a more uniform temperature and has smaller — if any — waves, lending itself to a variety of flora and fauna.
A "lonely" frog you might see floating on a pond lily pad probably actually has a host of neighbors amongst the cattails, phytoplankton and "pond scum." Turtles, fish, snakes, birds, and lots of insects take up residence within a pond's different zones.