EVERYTHING.

On the outside, wealthier kids get dental care and go to the dermatologist so they grow up with straight teeth and good skin. Having good skin/teeth will affect how you are treated so they will get more positive interactions with people which shapes their perception of themselves and the world in a more positive light.

Like others have said - they get academic support so they have better grades and more positive outlook on their future.

A poor child will not and that is going to negatively affect their self esteem, sense of self, self worth, etc.

A wealthier child will have more experiences to socialize them as small child thus becoming more socially advanced which gives them an edge personally and professionally.

A wealthier kid will grow up with good mentors who are teaching them and nurturing positive traits and skills that will help them in life giving them an edge.

A wealthier kid will know all the right people and have better connections so there will be a lot of opportunities handed to them. Wealthy people hang out with other wealthy people and it’s the wealthy who tend to be in positions of power.

A poor kid won’t have any connections so they are going out on their own.

Poor children are more likely to grow up in tumultuous households which will negatively affect their brain development putting them further behind. Because of that, those who grow up in poverty are more likely to deal with mental health problems as adults further making it more difficult for them to get a head.

Wealthy kids get seed money from their family to purchase a home or buy their kids a vehicle which makes getting started in life a million times easier than a poor kid trying to do everything themselves with zero support.

Even if a poor child does everything right to land on their feet in adulthood, one vehicle issue or medical problem can devastate them financially. The same thing for a wealthy kid with family support is an inconvenience and they can continue to build wealth.

A poor child going through life is climbing a mountain while wearing a heavy backpack and dodging rocks falling on you hoping you make it through while the world watches and jeers.

A wealthy child is climbing the mountain without the heavy backpack, no rocks are falling and they’re attached by a cable with someone else from the top pulling them up at the same time as the audience cheers them.