Hi @mdezrin and welcome to iNaturalist and to the Forum :)
Both iNaturalist and Seek are created by the same team, and they share a number of features, as you may have noticed.
Seek provides AI suggested IDs of live video footage. It is designed for those who want a quicker answer, or don’t want to make an account, or want something good for kids. Or who just like the live ID feature. Stuff you find in Seek may optionally be uploaded to iNaturalist’s database.
iNaturalist is more complicated. It has both an app and a website. The app is more simplified, and is focused on adding new observations to the iNat database. The website has a plethora of features.
However, you can use either platform however you want provided you follow the community guidelines.
Happy to answer any additional questions you have :)