One of the first and very important change is hwang junhyeon identity.

In the webtoon, he is an ordinary intern who wasn’t treated fairly well.

In the drama, he is football player who has his life fucked up by the chairman two kids.

I feel like aside from the drama, it introduces another layer to hwang’s character. It also makes us empathize with him and makes the soul swap has degree of consequence. Like his life already fucked up and now he even loses his body?? And that to someone who he consider as enemies.

Now this one I’m not sure since I haven’t read that far ahead in webtoon. This is what I heard from people who already read it. I don’t wanna get spoiled you know. So take it with grain of salt:

In the webtoon, from what I’ve heard that chairman in hwang body got together with politician’s daughter or heiress, anyway a powerful gal. I heard there are not much romance between them and he is using her to consolidate his position(?) Cause honestly the webtoon is kinda slower than the drama, and it doesn’t feel like he is using his chairman resources.

in the drama, she is his youngest daughter.

I feel like the change is to remove potential problematic element of chairman dating a young woman. In order to introduce reason a woman would help him, they added youngest daughter character. From outside perspective, people would see Banggeul and him in the same camp to get the company. But we know it’s because they’re father and daughter.