The most notable addition is the arrival of the “Party Time” Live Event, which unlocks new themed prizes and rewards. Of course, there are some other fun new additions, such as the new Duplicate Items feature.
It’s worth noting that when duplicating items, you still have to “pay” for the items before they can be placed/used.
There’s plenty of other new items as well, and many of them are featured in the video below.
As for the official patch notes, here’s what EA says of the Dance Party Update:
Your Sims will party all night with the latest update, where you can:
• Complete the Party Time Live Event to unlock the ultimate Sim Town Party House!
• Set the scene with a smoke machine, DJ deck, loveseats, and more
• Light up the night with dancefloors, disco balls, and smooth dance moves
Plus, keep your teen Sims entertained with the Teen Life and Prom Hobby Events that unlock teen bedroom items and prom outfits.