Delta Air Lines and Southwest Airlines are two of the most well-known airlines in the U.S. They are also two of the most different airlines in the U.S. Delta has its beloved Sky Club lounges, while there's no such thing as a Southwest lounge. Delta is conventionally classic, while pretty much everything about Southwest — whether it's the free Southwest checked bags or the controversial Southwest boarding style — is unconventional.

But in a comparison between Southwest versus Delta, they have some similarities, including both being two of the largest airlines in number of passengers served.

Here are the similarities and differences between the two airlines, and a side-by-side comparison to help you understand which airline is better for yu:

Where they’re based and where they fly

Winner for most flight options: Delta

The number of routes and destinations can be important, especially when trying to decide if you want to pledge loyalty to either Delta or Southwest and earn elite status. If you're flying often, you likely want options. While Southwest is certainly large, Delta's footprint nearly triples Southwest's.

DELTA ROUTE NETWORK

Delta Air Lines serves about 300 destinations in more than 50 countries worldwide. But what really helps Delta appear even bigger is that Delta is part of the SkyTeam alliance. That means the carrier partners with 18 other airlines that fly to more than 1,000 cities in 175 countries, enabling you to earn and redeem miles (and flex status) on far more than just Delta flights.

Delta domestic hubs

Atlanta.

Boston.

Detroit.

Los Angeles.

Minneapolis.

New York-JFK.

New York-LaGuardia.

Salt Lake City.

Seattle.

The airline’s key international markets include London-Heathrow, Mexico City, Paris, Seoul and Tokyo-Haneda.

SOUTHWEST ROUTE NETWORK

Southwest Airlines, on the other hand, flies to more than 100 destinations, most of which are located in the United States (with select destinations in the Caribbean and Latin America). The airline isn’t part of any alliance, so you have significantly fewer options to reach destinations abroad when flying Southwest.

Southwest hubs

Atlanta.

Baltimore.

Chicago-Midway.

Dallas-Love Field.

Denver.

Houston-Hobby.

Las Vegas.

Los Angeles.

Oakland.

Orlando.

Phoenix.

Travel credit card availability

Winner for most valuable airline credit card: Tie

Delta and Southwest both offer multiple co-branded airline credit card options for leisure travelers as well as road warriors.

Delta cards offer free checked bags for up to nine passengers booked on the same reservation. Southwest is a unicorn in that the airline doesn’t charge for the first two checked bags — a benefit that's available to all passengers, not just credit card holders.

Holding a co-branded Delta card puts primary cardholders and their companions in an earlier boarding group every time they fly Delta, regardless of their seat assignment. Select Southwest cards offer either EarlyBird Check-Ins or four upgraded boardings when available. Southwest has an open-seat policy and doesn’t assign seats before departure.

Some Delta cards offer discounted or free membership to Sky Clubs, which are Delta-branded airport lounges. The Delta SkyMiles® Reserve American Express Card comes with access to The Centurion Lounges by American Express, which is especially valuable this year now that American Express has cracked down on Centurion Lounge guest access. Terms apply.

Southwest doesn’t have any lounges for its flyers and therefore offers no access. If you want to luxuriate in a lounge before your flight, you'll need access elsewhere, such as through a Priority Pass membership.

Both airlines’ co-branded credit cards offer a discount on in-flight purchases, but the Southwest Rapid Rewards® Priority Credit Card also comes with a $75 Southwest credit and 1,500 Tier Qualifying Points.

Here's a roundup of the available credit cards from both airlines, and a snapshot of their perks.

DELTA CREDIT CARDS

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Rates & Fees

American Express issues several co-branded credit cards to Delta flyers. Here’s a closer look at the options.

Delta SkyMiles® Blue American Express Card

Annual fee: $0.

Welcome bonus: Earn 10,000 bonus miles after you spend $1,000 in purchases on your new Card in your first 6 months. Terms Apply.

Perks include 2 miles per $1 spent on Delta purchases and at restaurants, 1 mile per $1 spent on all other eligible purchases and 20% back on in-flight purchases. It also has no foreign transaction fees. Terms apply.

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Rates & Fees

Delta SkyMiles® Gold American Express Card

Annual fee: $0 introductory annual fee for the first year, then $99.

Welcome bonus: Earn 40,000 bonus miles after you spend $2,000 in purchases on your new Card in your first 6 months. Terms Apply.

Some of its benefits include Main Cabin 1 priority boarding, a free checked bag for up to nine passengers and 2 miles per $1 spent on Delta purchases, at restaurants and U.S. supermarkets. Terms apply.

Delta SkyMiles® Platinum American Express Card

Annual fee: $250.

Welcome bonus: Earn 50,000 bonus miles after you spend $3,000 in purchases on your new Card in your first 6 months. Terms Apply.

Cardholders get access to perks like a Global Entry / TSA PreCheck enrollment fee credit, 3 miles per $1 spent on Delta purchases and directly at hotels and status boost. Terms apply.