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

 * New Interactions based on emotions. (too many to list)
 * New ghost interactions
 * Angry fire ghosts can start fires.
 * Ghosts can talk about being dead.
 * Ghosts can possess objects
 * Electric ghosts can break appliances if angry, and repair appliances if they are happy.
 * Electric ghosts can electrocute others if playful (like a hand buzzer)
 * Emotional ghosts can spread the emotion that killed them.
 * Embarassment
 * Anger
 * Being too playful (laughing to death)
 * Exhaustion ghosts prefer to take it easy.
 * The new Emotions system. This a Huge new feature with a wide scope that has a major effect on game play and therefore has its own wiki article page
 * 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
 * New Walkstyles
 * Better Genetics
 * Create Parent, Sibling and Child
 * Genetically created Sims resemble the Sims they are created from
 * Ethnic-looking presets of faces and hair
 * Butt slider
 * 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).
 * Objects on walls and 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 (unlike Sims 3) 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 pillar is the height of the ground floor only, so there is a gap above it equivalent to the height of the foundation).
 * The Gallery
 * Traveling across worlds / neighborhoods without losing relationships, inventory or any other data
 * Emotions: each emotion allows unique interactions
 * Sims can resurrect other Sims from a book called "The Book Of Life", which Sims themselves can create.
 * Museums
 * Comedy clubs
 * Ability to change a Sim's aspiration without the use of special objects or game rewards
 * Ability to edit in CAS at any time
 * Merging of the Aspiration and Trait systems
 * Multi-level lifetime goals

New Objects

 * Rocket ships
 * Monkey bar
 * Gaming Rig

CAS

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

Little features

 * Breastfeeding
 * Delete and move objects Sims are using without the  cheat
 * Music from stereos now speeds up when the game's speed is changed. Television shows still remain in normal speed.

Features present in previous games

 * Cowplant (University)
 * Voodoo doll (Bon Voyage)
 * Nightclubs
 * Violin (FreeTime)
 * Grand pianos
 * Cupcake machine
 * Breast slider (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.
 * Teens are no longer shorter than young adults, adults and elders.
 * No opacity slider for makeup

Life stages

 * Toddlers

NPCs

 * Repairman
 * Firefighter
 * Police
 * Burglar
 * Gardener
 * Social worker
 * Nanny

Objects

 * Dishwashers and Trash compactors
 * Newspaper
 * Cars exist only as animated ambient decorations. Sims cannot own them or travel in them.
 * Alarm clock

Cheats

 * constrainfloorelevation

Build Mode

 * Basements, introduced in The Sims 2, are no longer available. (However, TS3's basement was included in the expansion pack The Sims 3: World Adventures and its associated Patch 1.6.6 for non-expansion users, not the initial launch)
 * Changing ground/floor elevation (the lot is completely flat).
 * Players cannot place foundations on some walls and not others.
 * The Sims 4 allows a maximum of three floors, but the foundation is no longer counted as a floor. (The Sims 3 started out with a maximum of 3 floors, but this was later increased to 5.)
 * Spiral staircases. (However, while all 3 previous games have included them, no base game has.)
 * 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.
 * Players cannot rotate and/or reposition (when placing a lot into a larger one) a lot when placing it.
 * Worlds are much smaller - about 25 lots per world (but Sims can move freely between them during a game, and there are two worlds in the base game).
 * The maximum lot size is reduced from 64x64 to 50x50 (and there are only about 2 50x50 lots per world). (The sizes of lots in the base game worlds are 15x20, 20x30, 30x40 and 50x50).

Live Mode

 * No more open world
 * Players get a loading screen when moving a played Sim to another lot or neighborhood (region of about 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.
 * Doors cannot be locked. (However, while door locking was eventually introduced into The Sims 2 and The Sims 3, neither base game included it.)