Sim Racing:

This sub-genre appears to be more complex than Simcade by having the handling model feel more accurate to the real world of motorsport, harder A.I, timing it right during practice & qualifying sessions, setting up your car (But there are some presets though), tactics on when to overtake your opponents, have the right time to pit-in to refuel the gas tank, change tires, brakes and driver (When it comes to endurance racing event).

However, they don't seem to be really well optimized with gamepads or mobile phones which makes them feel undrivable, plus they're much more recommended and optimized to use the racing wheel & pedal sets that support force-feedback, making it more drivable as the players have more proportion to control their steering, accelerating, braking and gear shifting.

Examples of Sim Racing:

• iRacing
• rFactor series
• Assetto Corsa Competizione
• Assetto Corsa
• DiRT Rally series (DiRT series spin-off but focused on the proper Rally Sim rather than Simcade)
• WRC series (Kylotonn 2015-2021)
• Richard Burns Rally
• Automobilista series
• Race Series (By Simbin)
• GTR Series (By Simbin)
• Live For Speed

Simcade:

This sub-genre is meant to be more accessible for most players, and old-school feel by having a little bit more forgiving handling model, slightly easier A.I, lesser setup options, catch-up/rubber banding being enabled as default, and using fewer tactics when it comes to overtaking your opponents, but still need the right time to pit-in (If it's endurance racing event) plus may not require to have practice and qualifying sessions.

They're great for both on controller pads (With analogue triggers/right stick to accelerate & brake like a radio control car) and racing wheel & pedal set (Better have force-feedback to have extra realism).

To me, this sub-genre felt more like for PlayStation/Xbox consoles and mobile phones in my personal opinion plus not every Simcade console/mobile/tablet player can afford or have room for their racing wheelset and cockpit too.

Examples of Simcade:

• Gran Turismo series
• Gran Turismo Sport/Prologue series
• Forza Motorsport series
• Project Cars series (Until the 3rd installment in the series)
• Enthusia Professional Racing (Konami's answer to Polyphony Digital/PlayStation's Gran Turismo and Turn 10/Xbox's Forza Motorsport series)
• Sega GT (Sega's answer to Polyphony Digital/PlayStation's Gran Turismo series)
• F1 series (Psygnosis (1996-2007) and Codemasters (2009-Present))
• DiRT series (Please note that DiRT 5 and DiRT Showdown are both completely arcade racers)
• Colin McRae Rally series
• WRC series (Evolution Studios 2001-2005)
• Rallisport Challenge series
• Real Racing series

Overall: I can see that Sim Racing is more associated with PC while Simcade appears to be more associated with PlayStation/Xbox home consoles and mobile phones.

Want to know more details? please watch viperconcept's evaluation of driving games in general.

https://en.wikipedia.org/wiki/Sim_racing

Additional notes:

• Two of this sub-genre of driving games are both great for the cockpit.
• Entry to mid-range wheel brands such as Logitech and Thrustmaster wheel for PlayStation/Xbox is good for Sim Racing, Rally Sim and Simcade.
• While the higher-end brands such as Fanatec, Moza, Ascher Racing, Simucube, Simagic and many others are more official for Sim Racing and Rally Sim over Simcades in general IMO.
• For the Assetto Corsa console & mobile version, it had an inferior driving model compared to its PC version counterpart, as the developer required to get the controls easier to be optimized for the controller pad (analogue sticks) and mobile phone/tablet's tilting.
• Assetto Corsa Competizione on last-gen home console versions (PS4 & Xbox One) has many issues.
• The Forza Horizon series is described to be a spin-off from the Forza Motorsport series by having a different sub-genre (Open-World Arcade Racer) to attract different kinds of car lovers, so the best comparison for that is always to be either Test Drive Unlimited or The Crew series because these 3 are open-world arcade racers. And why comparing Forza Horizon, The Crew, Test Drive Unlimited and whichever open-world arcade racers to whichever Sim Racer (iRacing, Assetto Corsa, etc.) and Simcade (Gran Turismo, Forza Motorsport, Enthusia Professional Racing, etc.) wouldn't make any sense? because of different gameplay.
• For Gran Turismo and Forza Motorsport series, I would personally treat them as collectible items (Due to my nostalgic memories from childhood to teenhood), the same goes with PlayStation and Xbox consoles too.
• Sim Racing and Simcade don't require to have the best crash physics because they're more designed for pure racing and they're not vehicular combat, plus based on the majority of motorsports' rules in real-life, ramming onto others is prohibited.
• Reiza Studios' trademark: Automobilista, sounds pretty similar to Auto Modellista (An arcade racing game IP published by Capcom).

P.S When I first joined Giant Bomb forums back in January 2021, I was more of a Simcade player because, by that time, I didn't have a proper racing wheel with force feedback until I bought one, mainly to use it to play Assetto Corsa Competizione on PC since June 2021, then suddenly I prefer Sim Racing more these days, also I've played iRacing, it's a pretty good game so far.