Are all fomular milk the same

Hi, I've question on formula milk for kids in the market.
There are so many category of fomula milk for different age.
The same age catagory milk has different price range.

A doctor told me that all those milk fomular found in the
market are all the same, higher price mike doesn't mean it
is superior then the lower price
milk. Is it true.

Thanks for share your taught