Specs are quantitative aspects of the option such as the price
Pros
Pro
Has a central package repository
A central repository provides more guarantees about the availability of the package. With requiring directly from repository urls, the entire project could potentially be taken down on a whim.
Because Jam only manages Javascript and only works on the client side, you have the assurance that any packages listed are AMD compatible for asynchronous loading.
Jam's only a front-end package manager, the rest of your server can be on a different architecture or framework. No matter what the architecture, Jam will integrate easily with it.