Total War: Three Kingdoms is - of course - going to feature certain aspects of the setting's specific 'Romance' elements, such as warlords' incredible feats of physicality and whatnot. This might not be to everyone's liking, however.
Total War: Three Kingdoms Romance Mode does away with all of that, focusing instead almost entirely on presenting the classic Total War experience through the lens of a more historically-accurate reimagination of the given folklore.
Records Mode is something that history buffs may enjoy quite a lot, all things considered. Sitting in opposition of the more fantastical Romance Mode, this type of gameplay is going to place a lesser emphasis on the famous Chinese romantic heroes, their duels, and their importance in combat, as well as deliver a more grounded and historical version of how it all came to be.
There are three major differences between Romance and Records modes in Total War: Three Kingdoms. Firstly, Romance hero units will spawn solo in combat, ready to take on dozens of other units head on. In Records, however, they will have a personal suite of bodyguards to keep them safe, as they will be no tankier/stronger than other similar units.
On a similar note, warlords will be much more likely to fall in battle in Records, and whereas fallen warlords in Romance have a chance to simply be wounded instead of outright dying, this chance is significantly lowered when you're playing Records.
Finally, Records will place a much higher emphasis on unit fatigue and tiredness, and players will have to take into account how fast their forces move about, among other things. This will, in turn, result in much longer matches where players will have to strategise much more carefully about what they're doing and how they're doing it.