How similar are the American drug selling gangs of the 1990s and the 2000s to the alcohol selling gangs in the 1920s and early 1930s?

Well (and this is a bit of a glancing blow for a top-level answer), both rum-runners of the 1920s and cocaine cowboys of the 1980s were able to run circles around law enforcement by being pretty ingenious and by having really deep pockets.

Case in point: in a few Prohibition-era waterfront mansions in Florida, you can find a secret stairway leading from a small, second-story room down to a secluded water entrance. (I've seen one in Ca' d'Zan, the John Ringling estate, and I believe there's one in Vizcaya, the John Deering estate, as well.)

The idea there is that your provider brings a motor launch up to the sea wall, offloads a few cases of hooch, carries it up to an out-of-the-way room (often with a vault nearby) without ever being in a place visible to guests or neighbors.

Cocaine is a little more portable than whiskey by volume - fits nicely in a guest's pocket, for instance. But moving it across national borders involved some equally resourceful tricks.

One system described in the great documentary Cocaine Cowboys ( <- you can watch the whole thing at that link, which I recommend ) had the cartels buying a towing company.

Instead of trying to land planeloads of cocaine from South America in Miami or points south, they'd fly up the coast to a ranch outside Tampa and load it into a junked car.

Then, one of the tow truck drivers would get an order to haul the car down from Central Florida into Miami from the north. No one was watching for the stuff from the north.

And if, by chance, the cocaine was discovered... the driver didn't own the car, and didn't know what was in its trunk. All the driver had was a purchase order to haul a car.

(The same documentary has an incredible story from a smuggler who talks about how his cigarette boat - a lean, high-speed motor boat - broke down with secret holds full of cargo. And they got towed in to port by the Coast Guard. )

The documentary doesn't really touch on the strange story of Leonin "Tarzan" Fainberg, who, from his office in a Miami strip club named Porky's, tried to broker a deal selling a Soviet military submarine to Colombian narcotrafficantes. He was caught doing that in 1997, but had already (three years prior) successfully sold Latvian helicopters to the cartels.

That's pretty comparable to Al Capone's armor plated Cadillac, I'd say.

So on that level - pockets about as deep as a government agency, able to hide well and obtain military-grade equipment - the two organized crime eras are fairly comparable.

Someone more knowledgable about guns could probably give a rundown on how a Thompson in the 1920s measured up against an Uzi in the 1980s... I get the sense Uzis were more efficient compared to the rest of their market than tommy guns were compared to what was available then, but I don't really know. They were both kind of identified as "weapons of choice" for the gangs of their respective eras.