Data modeling for Warehouse

I am learning about database warehouses and data modeling. I came across this blog post . In the section, "***DIFFERENT MODELS HAVE DIFFERENT PURPOSES***" the author mentions that depending upon the need of the business, there can be two types of data modeling: 1. Relational 2. Dimensional However, in both examples the author says that the modeling is done in 3NF form, I am confused, how is 3NF and star schema both used in dimensional model. Aren't they supposed to be fundamentally different? Lastly, if I understand correct, the relational data modeling is done for OLTP systems and Dimensional is done for OLAP systems, right?