I realize the basic difference is that a pond is smaller than a lake, but is there a technical way it’s determined what is a lake and what is a pond? The government must have some type of system simply for the purposes of labeling.
God, I know I’m going to get screamed at for this, but… unless its name is Huron, Superior, Michigan, or Ontario, it’s just a pond. Maybe, just maybe, we can throw Erie in there, too. Oh, what the hell, Lake St. Clair, too, since the idea of ships passing through ponds is kind of silly.
Erie’s bigger than Ontario, though shallower, if memory serves. In any event, the Great Lakes are more rightly called inland freshwater seas.
IIRC, there is no legal, technical difference. In general parlance lakes are bigger, but there are any number of exceptions to this. You name it what you want, and let other people figure it out. 
Could there be a distinction based on whether the pond or lake is connected to another, larger body of water by a river or stream?
It’s like the difference between hills and mountains. Everyone agrees that one is bigger than the other, but that’s about it.
As for the Great Lakes, I remember reading that geographers have (arbitrarily) defined seas to require that they be salty. Any body of fresh water, no matter how large, is considered a lake.
In British usage, usually pond is a small and artificial, someone digs a round or rectangular hole and pipes water in. A lake is either a natural formation, or at least is formed by water filling a natural hollow.
I think you attribute too much to the government’s Board on Georgraphical Names. They are more interested in promoting consistency in the name a particular feature is called, rather than enforcing consistency between different features.
However, it would appear not to work the other way, given the name of the Great Salt Lake. It would seem to apply, however, to the Caspian Sea, Aral Sea, Dead Sea, and Salton Sea, all of which are inland salt lakes.
Could the depth have something to do with it? I think of a pond as a place where you might be able to float a raft or canoe, but not any other kind of boat except the very smallest.
Ponds are generally spring or seepage fed, and have no inlets or outlets. Lakes have streams which fill them and streams which drain them. The waters of a lake should end up in one of the oceans as a result.
Does that apply to any lake as large as Lake Ontario, the smallest of the Great Lakes? If so, there’s at least a half-dozen others in the world (Victoria, Tanganyika, Nyasa, Chad, Great Bear, Great Slave, Winnipeg, and Baikal) that should properly be called inland seas but usually aren’t.
Fun fact: Lakes Huron and Michigan are at the same level, and the flow through the Straits of Mackinac has been known to switch directions. So they could technically be considered two parts of the same lake, which would make it the largest freshwater lake in the world.
Sure, why not? 
It’s really all completely arbitrary, of course.
The Dictionary of Geologic Terms has no description for pond and simply says a lake is larger and deeper than a pond but gives no quantifiable limits for either. Frankly, as a geologist (US), I like QtM’s description.
Hmmm… there’s something to be said for this. We say that a peninsula is a piece of land that juts into a body of water… so if they’re really two lakes, the lower peninsula’s not really a peninsula. But if it’s really a single lake, then it’s a bona fide peninsula.
So if a farmer builds a levee across a creek, and it fills to a body of water fifty feet across or so, you would call that a lake rather than a pond? That sounds iffy to me.
Personally, coming from Cleveland, my standard is that if you can see the opposite shore, it’s a pond, and if you can’t, then it’s a lake. But my standards might be a bit different than most of the world.
So, Lake Tahoe is a pond then? I’ll be sure to tell the residents of Lake Tahoe. I’ll also update those who live near the Salton Sea that they don’t live near a big salt lake either.
As opposed to those less common oceanic freshwater seas.
When I was in NewFoundland a few years back we were told that there were no lakes in NewFoundland! They are all called ponds. The fellow said “a lake is a hole in your boot!”. With his accent he pronounced lake as I would pronounce leak.
We were taking a boat trip on Westerbrook Pond at the time. Several miles long and quite deep and clear. There’s at least one waterfall that feeds it. Perhaps there’s another from the hanging valley on the South side. Don’t recall for sure.
Tahoe’s got streams feeding into it, thereby negating pond status by definition.
And Chronos, damming a stream creates an artificial body of water that is still fed by a stream and has some sort of outlet eventually.
I’m just giving standard usage with which I’m familiar, living on a Lake as I do (one of the great ones), having dammed a stream on our property to make a containment basin (or little itty bitty lake), and also having dug a hole and watched it fill up with water, thereby making a pond.
Besides, I’m over half Hollander by ancestry, it’s in my blood to be messing around with bodies of water. (Pops Mercotan and I built windmills too!)
I was really expecting the US Geological Survey to have “the answer”, but their answer is…well, it’s all in perception:
http://interactive2.er.usgs.gov/faq/get_answer.asp?id=787