T cells and B cells differ in the form of the antigen they recognize, and this affects which antigens they can detect. B cells bind to antigen on invaders that are found in circulation outside the cells of the body, while T cells detect only invaders that have somehow entered the cells of the body.
ABS, DWV, Solid or Cell Core sewer pipe. The solid pipe is composed of ABS at 99% while the cell core is composed of a cellular foam between 2 layers of ABS which makes the cell core pipe lighter.
But what is Sitecore really? From a developer's perspective, Sitecore is a platform which helps with the implementation of internet and intranet systems. Data modeling is done visually through its interface and all customizations are done in .NET, with the use of Sitecore's API to read and write data.