I will only say one for each:
For harder: 4th Generation have to try hard to find their own sound and identity because it is really hard to stand out when many groups are debuting and constantly dropping stuff, plus they are still competing with big 3rd Gen Groups that haven’t reach their peak and are leading such as BTS, BLACKPINK, TWICE, NCT, SEVENTEEN and more.
For easier: They are part of the moment when the Hallyu wave is at it’s peak so they get so much exposure and opportunities to gain fans.