here's a general list of differences from the system as found in legacy:

• Messages now support up to 3 lines of text

• The UI is slightly more compact compared to before, though not by much

• Wordwrap! No more having to delete a word and retype it on a new line, now the game will automatically move it to the next line

• Message previews are now much more accurate to the final message

• Talk sounds now play when you type

• Logic for visibility and positioning is much better than in legacy

• Typing should be more reliable than before; You can now play in 60 FPS for even smoother typing

• "Interrupted" messages continue to exist and simply turn small

• Expression selector now loops

• The previous little "..." icon has been replaced with a new animated icon as seen in Deltarune

• Better text pausing logic! (Ironically, it's much simpler, too)

• Redesigned modifier menu

• Many more colors for the color modifier

• Improved shake modifier

• New Wave modifier

• New Talk Speed modifier

• Re-enabling your portrait doesn't delete your whole message anymore

• Better field animation system

• Limited range for bigger rooms. Messages sent outside of this range will instantly turn small. (Messages in all caps have an increased range.)

• The heart sprite now also performs shakey and wavey movements for an improved preview experience

• (Not directly related to the system, but Papyrus was given new expressions based on supplemental sources like the Papyrus QnA(s) as well as expressions from his battle/date sprite)

• New voice system! Skins can now have different voices to choose between for a message. Different voices can have different fonts, sounds, ranges, you name it. Most skins will have a "Quiet" voice alongside their default one

i might've forgot some differences, but thats the gist of it