DT also changes OD bc of the weird DT calculation thing or w/e1Alone wrote:
It's because of the high od and cs, DT generally only affects bpm and the AR, while with HR it changes the whole song elements completely (higher OD, AR, CS and HP + the song pattern is changed a bit/upside down). Playing HR directly is hard because of the high OD and HP drain, causing you to fail a lot faster compared to DT ones (unless you mastered high OD before) and higher cs requires you to have more accuracy over your aim compared to the normal cs4 mapping style. Smaller circle (cs5) also cause the apporach circle to travel longer than bigger ones (cs4), making them look faster compared to cs4. People use DT to get used to AR10 first (AR8 + DT), then they move on to HR mod, I personally think that playing DT is better to learn AR10 compared to playing HR, as HR completely changes the song elements (Tho singletapping speed might be a problem when entering DT)