What is the difference between overall length and center-to-center of a cabinet pull? Where can I find this information?

Decorative Cabinet Hardware

Overall length is the total length of the pull. Center-to-center is the distance between screw holes on the pull body. The center-to-center distance is how you determine what size pull you need to swap out existing cabinet hardware.

This information can usually be found in the image carousel (the collection of images on a product page). It might also be listed as product dimension length with other details such as finish and material. Lastly, you can find overall length in the specifications section on the product page.

Towel bar vs hook, what’s the best?
Choosing between a towel bar and a hook comes down to your style preferences, types of towels your’re hanging, and your wall space.  Towel bars are typically used for more plush towels, heavier or longer body towels, and can potentially provide more airflow for faster drying. They usually hold towels more securely, if hung properly versus hooks.  Stylistically, they show off more color and hardware and noticeably contribute to your décor.  Towel hooks can hold both towels and robes and take up much less wall space. For example, you can mount one on a short wall right next to the shower to keep bath towels within reach - even from the shower itself. Style-wise, towel hooks are more discreet and tend to create more of a clean, minimalist look.  The biggest complaint about hooks is towels slipping off; however, Delta® No-Slip towel hooks are a great solution for this common problem. 
What are alternatives to towel bars in the bathroom?
Towel rings and towel hooks are the most common alternatives to bars for bathroom towel hanging. They are chosen for certain design aesthetics or to save wall space. Towel rings are commonly called hand towel holders because they are best for small towels, washcloths, and even decorative towels. They are usually wall mounted close to the sink for convenience. Towel rings can either be round, square, open or closed.   Free-standing towel countertop towel rings are also a good alternative to towel bars and provide the additional benefits of being portable and no-drill.  Towel hooks can hold either bath towels (aka body towels) or hand towels. They are great for mounting in small bathrooms, tight corners, or for a different look. Hooks make the most of wall space, as you can arrange their placement to create towel storage every family member on one wall. 
What are the best towel racks for small bathrooms?
The best towel racks for small bathrooms are compact towel bars and space‑saving hooks. A 12-inch towel bar is ideal for a single bath towel, and 8 or 9-inch bars fit well beside a sink for hand towels. If you have very limited wall space, a 6-inch double towel bar adds more drying room in a small footprint. Swivel towel hooks are another good option because they take up minimal wall space and can hold multiple towels or robes on separate arms.