Most Helpful Girl
Thicker eyebrows make you look younger. Especiall if they're straight and not arched. link
Arched and thin eyebrows make you look older. I remembered people stopped asking me for my ID when buying alcohol when I started to shape my eyebrows and make it like Rihanna's in your link, only a tiny bit thicker.
I think generally, thin eyebrows look better on most women, just because they look well-groomed. And some people think it's feminine, since men tend to have thicker eyebrows (=masculinity)
The last girl was some model who was just sporting the eyebrows about last year, when it was in trend on the catwalks. Looks terrible, especially with her dyed hair.
This, however, looks really... yummmmm link *Italians!*