Why is my windows 10 start menu different from the original

It looks something like this

The Start menu has had a makeover for the Anniversary Update (1607). The main change is that you no longer need to click on All Apps to open the list, scroll down a bit and you'll find it already open beneath 'Suggested'. To make space for this, Settings, Power etc. have been shrunk to icons on the left edge. Click the three solid line at the top left to expand them out to 'icons with names' as they used to appear.

More on the redesign here: This Is the New Win 10 Start Menu Launching with Anniversary Update

You can turn on and off the "Recently Added" and "Most Used" if you want and just have list like this....

Go to Settings > Personlization > Start and choose...

THank you so much , everything's clear to me now.

Good news.

I'd recommend keeping "Occasionally show suggestions in Start" turned off. All it seems to do for me is stick a random advert for a Fibre cable provider in apparently at random.