Who's Flying this Plane?

That's a code share between Delta and Virgin Atlantic. If you would be happy flying on either of those airlines, you'll be fine. Your reservation should tell you what you need to pay for.

"Operate By" means exactly that. So if the flight says, "Operated by Lufthansa," you will be on a Lufthansa aircraft, flown by Lufthansa pilots, and serviced by Lufthansa staff.

Because of a thing called airline alliances, the same physical flight can be sold/ticketed by partner carriers within the same alliance. Each Alliance will have their own dedicated carriers for certain routes/regions. As an example, Star Alliance has the likes of United, Lufthansa, British Airways, Singapore Airlines, and many others, as its carriers. If you go to the United website and try and book flights to/from US and Europe, you'll find a lot of flights that are operated by Lufthansa, and other partners, like SAS, Swiss Air, etc. You can go ahead and purchase this flight through United, but it means that you have to go back to United for any major changes, rather than the operating carrier. So if you actually would rather be on a flight operated by Lufthansa and the price is the same on either website, why not just purchase the flight directly from Lufthansa.

Back to your case, yes, your flight will be on said domestic carrier. and NOT on the European carrier that is ticketing it.

If it is operated by Virgin Atlantic, you will be on a Virgin Atlantic plane with whatever amenities Virgin Atlantic provides.

I'm not positive, and the policies can vary from airline to airline, but I believe an International route, regardless of whose name is on the side of the aircraft or on the uniforms of the crew, pretty much has free drinks, food, etc. Even if United gouges passengers for every little thing on a domestic flight, it seems to me that on a flight a few years ago from Chicago to London, food and drinks were complimentary (ask as often as you want for water, juice, etc., and complimentary wine was served with dinner), so if the crew had had British accents, you'd have thought I was on a British Airways flight, in some respects.

A notable exception is Icelandair, who charges for food and alcoholic beverages on their own flights from North America to Reykjavik, but you can bring you own flood on board, as long as you get it past Security. Times may have changed some of this for other carriers, but it may not be as strict as you imagine.

Do not assume you will get the same quality service with a code share. Last fall I traveled on round trip ticket bought on United Air website. The segment from Toronto to Athens was code share Air Canada Rouge. I made the mistake of assuming it would be comparable to a United international flight. It was not. No free movies (no seatback video screen), no free drinks, dirty, overhead seat lights not working, and flight attendents either not working or too few that they didn't even clear meal trays until prep for landing. The return flight from Europe was on a United plane and had none of those issues.

I see you are asking about different airlines than my experience but wanted to point out that travelers must not assume code shares will be comparable. (And after returning I found lots of bad reviews on this website and others about Air Canada Rouge.)

Virgin is a great airline. Even their US domestic runs on Virgin America are a cut above. I'd fly Virgin over any other airline.

Virgin is actually 3 different airlines.
Virgin Atlantic (UK based)
Virgin Australia
Virgin America

Just because an airline is flagged in Europe doesn't mean it's superior service to airlines flagged in the USA. In fact, our airlines learned a lot of their fee-charging games from the Europeans... For instance, if you fly British Airways, you won't be able to select your economy-class seat more than 24 hours in advance of take-off without paying a substantial fee for the pleasure. Also, most European airlines have much stricter checked and carry-on luggage rules than American carriers (you're carry-on you just traveled with on United may incur substantial fee on a European partner).

So, it pays to inform yourself by going to an airline's web site and researching fee structures and cabin/service amenities. I find USA-flagged trans-oceanic service to be comparable to European trans-oceanic service. You might also want to get familiar with the SeatGuru website/app (if not already).

Lastly, if/when you are booked on a code-share flight , if something goes wrong, the people you call is the airline who issued the ticket - not the airline who's name is on the plane (generally speaking).

Thank you all for the input.

The term I've seen for who's actually flying the plane is "metal." For instance, in your first example, although your flight will have a Delta number, it is said to be "Virgin metal."

In addition to wanting to know about amenities, it's very important to figure out whose metal you're flying so you know where to check in. You always check in with whoever is actually flying the plane. So, in this example you go to Virgin Atlantic checkin, not Delta checkin. In large airports, going to the wrong place can waste a lot of time.

And yes, Virgin Atlantic is a full-service airline with a good reputation. Air Canada Rouge, not so much (it's not at all the same as regular Air Canada, and it seems they're shifting more trans-Atlantic routes from regular to Rouge).