Is there a clear distinction between these two beings?

In norse mythology dark/black elves (svartalfr) are often interchangeable with dwarves (dvergar). It is implied that they either are the same or live in the same place(svartalfheim). Though there is also Nidavellir where dwarves are said to dwell. Both avoid the light, and at least the dwarves are master blacksmiths. I would like to think svartalfr are also are also blacksmiths of remarkable skill but cant offhand remember where I have heard that. Also some say that the svartalfr are just a nickname of sorts for dvergar. Then there are the ljösalfr(usually just alfr) that most would think of is they think about elves. Powerfull magic users and warriors, immortal friends to the gods, sometimes sleep with mortals producing great heroes. Apparently their appearance is like humans expect that they appear more beautiful and glow. Basically a glowing version of lord of the rings movie elves. Pentagram was once used to ward of malevolent inviduals and called "elf cross". Which is kind of weird considering I have never heard of elves(except for dark elves) being anything worse than annoying pranksters. Said to be originally some kind of fertility gods. Oh and apparently if you're really, really badass you can ascend into an elf upon death. Which probably would have pissed of some people this happened to. Valkyrie: "sorry, you cant be einherjar and drink and eat great food all day, your going to be an elf and stupid people in the future will think of you as a peace loving hippie" Badass viking: "NOOOOOOOOOOOO!!!!!!!!!!!"

O-o i think there is some form of difference, at least today thanks to DnD and other RPGs, but i'm not sure if there originally was.

I’m not so sure but as I remember the original elves were human-sized and regarded as minor fertility gods while the dwarves are short people with long beards that are good in metallurgy. Unluckily, modern usage of the terms made them somewhat synonymous.

Actually, I'm pretty sure they are still distinct. At least in countries where their legends originated in. Here in Finland, though perhaps not the place of origin per se, for example there is the word Haltia which means elf. As in ljösalf, witch most of the people think of as the lord of the rings variant or blood elves, or night elves etc. Then there is the word tonttu which means mini sized and often bearded dudes following around santa, protecting houses, sauna's and various other places, and generally being helpfull if not pissed of. Then there is kääpiö, which can mean either little people or dwarves of the kind described by tolkien, bearing much resemblance to the kind appearing in the eddas. And I really would like to keep the roleplaying games out of this unless discussing that variant specifically. Its dangerous to confuse the original entities with the thoughtforms formed more recently by human thought. The precense of elves is undeniable in certain places if one can listen and see with clarity. My sources: prose edda. About 10 books on asatru, runecraft and norse myths, and having visited places where elves are said to have once dwelled(still do in my opinion) Oh, and the stories of my grandparents, parents and teachers.

Based on typical description, how tall is an elf? How about a dwarf?

In modern times, from around middle ages dwarves have thought to been a little over half the height of average human, or to the chest level, pretty well built though. Before that both elves and dwarves were depicted as about the same height as humans, a little more or less depending on the source. I have no idea how elves came to be described as little in modern times as that never interested me very much. And I make no claims about elves from other places in the world except for Scandinavia and other places where Norse mythology has dwelled.

You said that elves are described as "little" in modern times. How little are they?

I was referring to chrismas elves, which are what most people propably think of when they hear the word elf. They are supposedly sized like human children, though the finnish version can be anywhere between squirrel and grown man depending on source. Artistic liberty I quess

Is there a female dwarf?