Even though Threads and Twitter have a lot of similarity, but there are lot of differences too among the two. The first difference is that one can sign up for Twitter independently while as one has to use his Instagram account to sign up for Threads. In addition, Twitter imposes a limit of 280 characters for unverified users and threads has a limit of 500 characters for all of its users. If you want to delete Twitter account, you can do so independently. But to delete your Threads account, you have to delete your underlying Instagram account.