New
#1
Welcome to Ten Forums.
Where did get that higher example pic? Did you find it online?
Note that in the pic there's a mouse cursor hovering over the button. Yours (and mine) will change to that thin blue line around the Save button when you hover over it. That, I think, is the explanation for the different look.
I had a similar situation a while back, all the dialogue buttons appeared "thicker" suddenly. Turns out in my case it was because I had switched from a 1080p TV to a 1440p monitor, the new monitors default sharpening was way too aggressive leading to a larger button border. Turning sharpening down to a minimum improved things no end, on text as well as buttons.