Sims 3 vs Sims 4 Horses (Part 1)

Sims 3
In the Sims 3, horses came with Sims 3: Pets alongside cats and dogs. They weren't a separate expansion pack.
In the Sims 3, you can get a horse by adopting one for free. After you adopt a horse, the horse will be brought to your house in a vehicle. You can also befriend a wild horse and add them to your family. You can go to the Equestrian Center and buy one. The easiest way is creating one while you're creating your Sim. In the Sims 3, Horses are selectable and you can control them like you control your Sims. Horses in The Sims 3 have 6 needs: Hunger, Energy, Social, Exercise, Thirst, Bladder. Horses can groom other horses, can play with them, and a male and a female horse can try for a foal. After a few days of pregnancy the mare will bear a foal. the foal can be nursed. when foals are near their mother, they are very happy, and miserable when they're separated.

Sims 4
Horses in The Sims 4 came in a separate expansion pack Sims 4: Horse Ranch. Unlike The Sims 3, Horses in The Sims 4 cannot be controlled like Sims. You can get a horse by rescuing one for §250 or buying one for §1000. After choosing a horse, your Sim will disappear and come back with the horse. You can then rename the horse if you want. You can also go to the Equestrian Centre and rescue or buy a horse. You can create one in CAS and customize it the way you want. you can Choose the horse's traits and breed. Unlike The Sims 3, you can now create a foal and elder horse as well.
Horses have 5 needs: Hunger, Energy, Fun, Social and Hygiene.
There are few ways you can take care of your horse. Your horse will get dirty, so You can brush their coat, clean their hooves to increase their hygiene.
Horses also have emotions. when they get scared you can try to calm them down. You can also hug your horse, rub their neck, scratch their neck, talk to them, tell jokes. When you become good friends, you can also whisper to your horse and mellow out when your horse is happy.
You can encourage horses to socialize with other Sims, other horses, mini goats and mini sheep. Male and female horse can breed with each other and produce a foal.