Hi molona, that's a very good question and I think everyone asks the same question before getting started with Buffer.
The huge difference between using Buffer and a Twitter client offers scheduling such as Tweetdeck or Hootsuite is the ability to save time and have everything in one place.
If you use Tweetdeck or Hootsuite's scheduling feature, there is a need to set a future date and time whenever you try to schedule a tweet. On the other hand, with Buffer, the time and date is only set once before you start, and all the tweets that you schedule will go out during the time set.
If you are worrying about creating a pattern that your followers can spot easily, they offer a robust settings page that you can use to set different time for different days of the week. If you want to change the time, just do it from the settings page and all the tweets in your buffer will adjust themselves accordingly.
And they do scheduling for platforms link Linkedin very well. All of the scheduled updates coming from Buffer will have a thumbnail together with a proper title and description, which is not the case with some of the social media dashboards out there.
You really have to give it a try to appreciate Buffer (it has a free plan anyway).
This might sound like I'm promoting them heavily but it's really not, just a post coming from a happy customer.
Feel free to add more questions.