Depends on what you want to know. Montgomery County aka MoCo, is probably the most diverse county in MD in terms of people living there. It's also one of the wealthiest in the state and country. Has some of the best public schools in the country.
In terms of Industry: Tech and Biomedical research are pretty big in the area. NIH, FDA and DoE are all in the area.
Some of the main areas in MoCo
Silver Spring: This is a mid-tier city with some pretty decent nightlife and restaurants. On the border of DC but about 15-20 mins from the "action of DC". It's a mix of suburban and urban. On the weekends it gets pretty interesting. There's a square where people come to eat, shop and hang out. It's a mix between young people, young couples, teens, new families and older couples. It's a pretty chill place. Very diverse in terms of people's origins.
Bethesda: Creme de la creme. Used to be a residential enclave for the well connected in DC, but lately the city has taken on a life of its own. More businesses have come into the area. Very pricey area to live in but it's usually ranked as one of the top places to live in the US. Also a very well educated populace. I think close to 40% of the adult population has a Masters or above. Median household income in the area is well about $150k annually. That said, area can be a bit
. But outside that it's pretty cool. I'd say it's similar to Silver Spring in terms of feel i.e. that suburban mixed with urban feel, but it, Bethesda, is like 2 or 3 levels above Silver Spring, but not as diverse. I interned there for a summer in college and I remember walking around during my lunch breaks and not seeing that many people that looked like me. Bethesda is very close to NIH and it's about 10 min North of DC proper and about 15 mins North of Georgetown. All in all a really nice place.
Rockville: Formerly a very residential town that is now trying to emulate Bethesda. About 15 mins north of Bethesda. It's a pretty chill spot. The town square has some cool restaurants and newly built apartments, but overall it's offerings are pretty limited. Pretty well to do area although not as wealthy as Bethesda. Some areas of Rockville are a tad more rural. About 25 mins north of Bethesda.
Germantown/Gaithersburg: About 10-15 mins north of Rockville. A very residential area but there is a mall/shopping center RIO that opened up in the area that's actually quite nice. Got some good restaurants and bars for people who don't want to drive all the way out to DC for a Friday night. Technically, these are different, distinct towns, but since they are pretty close by I grouped them together.
Potomac: The 1%. Potomac is to DC as the Hamptons is to NYC. Rural landscape with some home sitting on straight acres of land. My former college roommate invited me and some friends to watch the Manny vs Mayweather fight at his place way back when. Dude lived in an absolute mansion. I got home later that day and checked the home value of his house. $3.5 million. Potomac is on the very edge of Western MoCo. Borders the Potomac river and is about 30-40 mins from DC proper.
Takoma Park: A working class city with a very large Latino community, especially Salvadorians. There's this restaurant I go to for some Pupusas
. Not too much in the city. Outside of Latinos, there's also a sizable African immigrant community.
Overall MoCO is pretty cool. Pretty diverse in terms of the population, close to DC and pretty well run. It is quite expensive if you're looking to buy a home.
what you are talking about?
....but hey if NYC and it's "diversity" is your thing
"You like it I love it" 
