Well, apparently there is a lot more stuff for Model 3 in 18.24 then for S/X
Model 3 US/Canada
With this release, Model 3 now connects to available Wi-Fi networks. Tap the LTE icon at the top of the touchscreen and select the network you want to join.
Also, added cabin overheat :
Cabin Overheat Protection:
When active, your vehicle prevents the interior temperature from exceeding 105F/40Cfor up to 12 hours after you exit your vehicle. This feature is turned on by default but can be disabled by tapping Controls > Safety & Security.
Cabin Overheat Protection stops operating when the battery energy level is 20% or less.
Driver Profiles Update - Model 3 - US CA
Whenever you adjust the driver seat, two additional shortcuts will appear in the Driver Profiles drop-down. This allows you to quickly change the position of your steering wheel and side mirrors.
Moreover, the climate control settings are now included in the features saved with your Driver Profile.
And if you have Autopilot:
Model 3 can now be summoned in and out of narrow parking spaces using the mobile app. To enable this feature, tap Controls >> Autopilot >>Summon. To learn how to initiate, cancel, and customize Summon, refer to the Owner’s Manual.
For S/X they added another language options: Spanish (If you're in Mexico it seems)
Spanish is now available as a language option for your vehicle. To choose Spanish, tap CONTROLS > Settings > Language & Units. When selected, the touchscreen will display in Spanish. Voice commands, navigation, and Media Player will respond to Spanish