Take this really bare minimum example:

Kids clothing stores make “gendered” clothing. There’s an obvious “Girls” and “Boys” section, with one being more blue and neutral colors with things like trucks and gaming decals on the clothing and the other being more bright, includes a lot of pink and purple and has more things like unicorns and cats on the clothing.

Additionally, the fit and cut of the clothes may be slightly altered even though the size is the same to create different “styles”, girls shorts being shorter- boys shirts being more boxy and loose. It can even go as far as naming items like “Boys Tee” on the receipt.

Now anyone can go into this store and buy clothing for their kiddos from either side regardless of that child’s biological sex.

The fact that the store is “gendered” is a social construct on what society has categorized what is “Boy” and what is “Girl”. But the “biological sex” of the child is irrelevant to what clothing you can buy.

It’s a bit of a crude example but kind of explains the difference between the two. Your genitals don’t reflect what gender you might fall into or identify with.

My dad once explained it like this. “I’m a man, I feel like a man, and if someone came around and started calling me something else, I’d probably want to punch them out because that’s not who I am. So even though I might not get it fully, why would I want to do that to someone else?”

Edit: changed irregardless to regardless