Can I use both at once?

Yes, and it is often the best approach for the first few weeks: you compare your rates and keep whichever works for you. The one condition is adapting the profile to each — copying a Tinder profile onto Hinge unchanged gives a poor result.

Which one has more people?

Tinder, by a wide margin, in almost every city. Hinge has a smaller base but a more consistent one in intent. In a smaller town the volume difference alone can decide it: an app with no users nearby is useless, whatever its qualities.

Is Hinge really more "serious"?

It is designed to be: longer profiles, prompts to fill in, an incentive to comment on a specific element rather than swipe. That filters up front. But real intent depends on people, not on the app — you find both everywhere.

It sits between the two, with a rule of its own: in heterosexual matches, the woman messages first. That sharply reduces the volume of unread messages, and changes the nature of the first exchange.

Hinge or Tinder: which one to choose

Two different logics

On Tinder, the unit of decision is the photo. You see an image, you swipe, you move on. The format encourages volume: many profiles seen, very little time on each. The winning profile is the one whose first image stops the thumb.

On Hinge, the unit of decision is the element. You do not like a profile, you like one specific photo or one specific answer, and you often have to comment. The format slows everything down and rewards whatever gives someone something to say.

Direct consequence: the same profile is not worth the same on both. A great photo with nothing around it is excellent on Tinder and mediocre on Hinge. A rich but visually average profile does the opposite.

What each one asks of you

Tinder

A flawless lead photo — everything happens there.
A short bio, whose job is to remove a doubt.
Volume: the sorting happens through numbers.
A first message that makes up for the profile's thinness.

Hinge

Six photos that each say something different.
Prompt answers you actually worked on: that is where you get read.
Fewer likes sent, but chosen and commented.
A first exchange starting from a specific element, not from zero.

Which to choose, based on what you want

You want to meet a lot of people quickly → Tinder. Volume is its real advantage.
You are after an ongoing relationship → Hinge. The format filters up front, which saves you time even with fewer matches.
You are stronger in writing than in photos → Hinge, without hesitating. Tinder will never let you show it.
You live in a mid-sized town → Tinder first, for a mundane reason: the user base. An app with nobody around you has no quality that compensates.

The mistake to avoid

Copying your Tinder profile onto Hinge unchanged. Prompts left blank or filled with a single word immediately signal someone who did not play along — and on Hinge those answers are most of what gets read.

In both cases the lead photo remains the starting point: the rules do not change from one app to the other. What changes is what you are asked for on top.