I think that they are looking at slightly different things. As I understand it white flight criticizes that white people (at a population level, not each white

I think that they are looking at slightly different things. As I understand it white flight criticizes that white people (at a population level, not each white person obviously) displaying behavior that suggests that they don't want to live in a multi-cultural society. Alternatively, white flight might be a criticism of defacto segregation either due to redlining or due to minorities being priced out of white neighborhoods. Gentrification refers to the residents of areas that are low cost and low income being priced out by an influx of more wealthy residents. It's also used to refer to development designed to cause that influx. Race is only a factor to the degree that wealth tends to correlate with race in the US.