It is selecting genes through breeding or doing the same thing in a laboratory.
It is a completely different mechanism. The best way to simply describe this is perhaps to say that in selective breeding you are allowing random mutations to happen naturally - IOW allowing the plant to naturally “adapt” to it’s environment. This is crucially different in that you are not going in and saying “oh these genes are the ones we want let’s only bring those out” but rather “these are the characteristics I want, let’s select the organisms that display those”.
To put it another way: in selective breeding you are selecting for a collection of characteristics. A great example is saving seed from a crop you have grown. Those seeds will always do better in your specific environment than commercially purchased seeds of the exact same cultivar. Why? Because there are small random mutations across a number of genes that are better adapted to your specific environment to produce the characteristics you want. Those genes are often not actually understood nor is the effect of different combinations of genes. By working backward from exhibited characteristics you are working from known successful combinations.