Fab.com is not some amazing technology, it's not going to change the world with 1s and 0s, Fab is a brand and the way their website is presented is important to their brand. The
style of something is the sum of all its parts, it's the way something is designed and presented. Sure, on the face of it having a clock next to the time to go is meaningless and sure having a tag next to the price is meaningless, but when you have a website made up of lots of things like that it becomes their "style".
To me it is absolutely certain that ToM made a concious effort to copy the style of Fab, through the composition and presentation of individual elements and the layout of the site.
Branding is very important and can very easily confuse consumers, maybe Fab are being overzealous and should have just asked ToM to stop copying their branding, but to claim that because lots of websites have clock graphics next to their timers that this isn't a copy is silly.