'Portland cement' is the name of the stuff you mix with sand and water, maybe some gravel, to make concrete. The structure is concrete, the ingredient is cement.
Portland cement is staight-up cement powder - pure and simple. It is mixed with sand and water. That's all they used many years ago. The vast majority of people these days use Ready-mix Cement which is mixed with water. Cement powder is only known as Portland Cement.
