Since you're only concerned about the cars, we'll leave out the long, winding road of how they got there, which includes some business and politics.
Le Mans is part of the World Endurance Championship, which for this 2024 season includes three classes:
Hypercar - the top class, of "prototype" race cars, usually run by factory, or factory-sponsored teams, and when the cars are made available, private customer teams. Currently, Porsche is the only one to have offered customer 963 cars, run by JOTA, Proton, and JDC (in IMSA).
Within the Hypercar
class, cars built to one of two different rulesets/specs are eligible --
LMH (Le Mans Hypercar) - which is a more liberal set of regulations that incorporates a hybrid drivetrain and AWD, via a front motor-generator unit. The chassis are designed and manufactured by the OEMs, and the original intent was for them to evoke road cars for brand affinity. In practice, it hasn't really worked out that way, though the forthcoming Aston-Martin entry will conform to that spirit. Ferrari, Toyota, Peugeot, and Iso Fraschini all chose this spec.
LMDh (Le Mans Daytona hybrid) - this is a less advanced, but more budget-friendly set of rules, with chassis designed by one of four suppliers (Dallara, ORECA, Multimatic, and Ligier), and spec hybrid systems supplied by Bosch, meaning everyone incorporates the same single-supplier system into their drivetrains. Their hybrid components are contained within the drivetain, not a separate front MGU, so these cars are RWD only. Porsche, BMW, Cadillac, Lamborghini, Alpine, and Acura* have built cars to this ruleset. (*Acura races its LMDh only in the IMSA Weathertech SportsCar Championship, in the GTP class, in the U.S.)
LMP2 (Le Mans Prototype 2) - this is a spec, cost-controlled prototype class, with chassis sourced from one of four approved manufactuers (same ones as LMDh). However one -- ORECA -- dominates the entry list because it built the fastest car, and as a Pro/Am class with private customers, nobody is going to buy the slower car. They all utilize the same
Gibson Technology built V8 engines, which is based on a Nissan design. Pro/Am means its competitors include only professional drivers, but very rich guys who can afford to spend millions per season to go racing in the big time, with the pros, by buying rides as customers with established teams, or even starting/bankrolling their own teams.
LMGT3 (Le Mans GT3) - this is the first year the WEC and Le Mans have adopted cars built to this ruleset, but it has been around for a long time, and is very popular, raced in various different series, also mostly Pro/Am, but the all-pro DTM series has also adopted GT3 cars as well. These cars most resemble the street cars we can buy, but carry price tags of between ~$500-800k each. They're derived from the road cars, but are pure race cars, albeit built with costs and ease of maintenance/driveability in mind. Cheaper to buy and race, but still not cheap. The success of the GT3 class has come about because its popularity has made good business cases for the OEMs to build and offer these cars and the two have fed into each other. Mercedes, which sinks most of its racing budget into F1, also offers GT3 cars, and provides some backing (in the form of professional drivers from its factory roster) to private teams to run them. Others also follow the same model.
That should get you started.
