Yes...I feel your pain. Took me a while to figure it out when I was shopping a few months ago.
The price of the bike is the clue for level of components. Since the price point dictates everything for the major companies. For the major brands, they will match each other on price and components. So a $500 Trek is similar to a $500 Giant and a $500 Specialized. Move up to $700, the same is usually the case, and up to $1,000 the same is usually the case. Rare to see a $700 bike with $1000 level components or a $500 bike with $700 level components. The only thing I saw was the 2020 Rockhopper Comp 1x, which I got has a MicroShift Advent 1x9 drivetrain instead of the 2x9 drivetrain that is in all the other sub $800 bikes. So its a similar drivetrain to the $1000 bikes in function, from a different company. Its an inexpensive system, but its getting rave reviews and when I rode it, I personally liked it better than the 2x9 setups. Thats why I went with that bike, seemed like a little more value and performance for a little less money than the other bikes in that price range.
What I DID notice between the brands was feel and fit. They have different frame geometries and for me the Rockhopper felt the best. The Trek felt either too big in the Large and too small in the Medium and the Giant to me was ok..just not great.
Thats the important part call around find a place that sells a few brands and ride them all a few times, then decide which one is in the price range she wants to be in feels the best.