Comparison between The Sims 3 and The Sims 4

The Sims 4 has many features new to the series; at the same time, many features have been lost since The Sims 3.

New features

 * Emotion system. This a main feature with a wide scope that has a major effect on gameplay. Unlocked interactions based on emotions.
 * Create a Sim: Hands-on interface.
 * Directly pull and stretch the heads of Sims and even their bodies
 * Body parts can be enlarged or shortened
 * Walk styles
 * More genetics options
 * Create a Sim's parent and sibling, in addition to child
 * Non-Caucasian presets of faces and hair
 * Build mode: Improved and easier
 * Moving and rotating rooms and houses.
 * Saving rooms (for sharing, copying, or moving to another lot).
 * Enlarging objects (objects can be scaled using shift+[ and shift+]. It's useful for decorative objects).
 * Windows can be placed at any height.
 * Curved fences/railings. (The size of the curved section can be adjusted. They can be elliptical. They must be multiples of 90 degrees. The minimum size for a 90 degree curve is 2x2. Curves can define the edge of a floor (with or without a railing), but only when convex (a floor tile on the outside of the curve is not rendered correctly) ).
 * Players can easily adjust the height of a floor at any time (including after building floors above it), but there are only 3 supported heights and the height of a floor must be same for the whole lot.
 * Roofs on the same lot can have different patterns.
 * Columns (pillars) automatically scale to the height of the floor/story, but when placed on the ground with a building that has a foundation, the column is the height of the ground floor only, so there is a gap above it equivalent to the height of the foundation.
 * The Gallery content sharing system.
 * New ghost interactions
 * Ghosts can now possess any object, instead of only certain objects.
 * Angry fire ghosts can start fires.
 * Electric ghosts can break appliances when they are angry, and repair appliances when they are happy.
 * Electric ghosts can electrocute others when they are playful.
 * Emotional ghosts can spread the emotion that killed them (embarrassment, anger, playful).
 * Exhaustion ghosts prefer to take it easy.
 * Traveling across worlds / neighborhoods without losing relationships, inventory or any other data.
 * Multi-level lifetime goals.

New Objects

 * Rocket ships
 * Monkey bar
 * Gaming Rig
 * Objects with emotional auras

CAS

 * Pants are tucked in under boots
 * Hats/headgear and hair are now separate

Little features

 * Breastfeeding
 * Objects that are being used by Sims can be moved or deleted without the  cheat.
 * The television and radio speeds now go faster depending on the current speed of the time.
 * Teenagers can "Mess Around", which has the same animation as WooHoo.

Features present in previous games

 * Cowplant (The Sims 3 Store)
 * Nightclubs (The Sims 3: Late Night)
 * Violin (The Sims 3 Store)
 * Grand pianos (The Sims 3: Late Night)

Lost features
Features that existed in The Sims 3 core game but not in The Sims 4 core game.

CAS

 * Create A Style is no longer available. Clothes and objects are available in pre-defined colors only (unless players change it through Mods).
 * Teens are no longer shorter than young adults, adults and elders.
 * No opacity slider for makeup
 * Body hair
 * 5 traits per Sim. Traits modify behavior / AI in The Sims 3.

NPCs

 * Firefighter
 * Police
 * Burglar
 * Social worker

Objects

 * Trash compactors
 * Newspaper
 * Cars exist only as animated ambient decorations. Sims cannot own them or travel in them.
 * Alarm clock
 * Landline telephone
 * Bathroom stalls / urinals
 * Lounge chairs
 * Rabbit Holes

Cheats

 * Unrestricted ability to modify the terrain

Build Mode

 * No pond tool. (however natural pools are a feature in The Sims 4: Get Together)
 * Steps cannot have different railings on each side. They can only have a railing on just one side if one side is against a wall.
 * Create A Style is no longer available. Objects are available in pre-defined colors only.

Editing World

 * Players cannot place new lots or change the size of existing ones, nor can they place decorations in the world.
 * Worlds are much smaller - between 10-25 lots per world (but Sims can move freely between them during a game, and there are three worlds in the base game).

Live Mode

 * No more open world
 * Players get a loading screen when moving a played Sim to another lot or neighborhood (region of 2 to 5 lots), but not on moving between the current lot and the open space of its neighborhood.
 * When Sims in the same household are on different lots, there are limited actions available for those not on the current lot, and players can switch to the lot of another Sim but that will cause a loading screen.
 * Story progression has been removed. Sims the player does not control directly will eventually die, but they won't get married or have children on their own, among other things.