One of the characteristics that can vary within a type family is weight. Some typefaces have an enormous range of Weights and while there were no consistent naming conventions in the Typographic world, it’s usually pretty easy to guess from looking at the full name of a font what its weight is. For example, Extra Light, Roman, Semi Bold, Bold, and Black.
The second characteristic of different family members within one typeface is Width. Again, the names are pretty easy to understand just by looking at them. Terms like Ultra-Condensed, Condensed, Roman, and Extended. The third characteristic that can vary within a family is Slope, depending on the typeface Slope can refer to an Italic version or an Oblique version. Oblique, which you see here, is simply a slanted version of the Roman. The Italic is a slightly more inclined and rounded version of the Roman or upright font, and often features letterforms that had design characteristics, which differ from the Roman. If there are variations in all three, Weight, Width, and Slope, this is the order in which the naming conventions work. First, all of the members of the type family will start with the name of the typeface, then the Weight, then the Width, then the Slope. For example, Helvetica Neue which is the Name of the typeface, Heavy, which is its Weight, Extended which is its Width, and Oblique, which is its Slope.
When you are naming fonts, always follow the NWWS pattern: Name, Weight, Width, and Slope