Because fonts are created to serve different purposes, they come in different formats and are licensed differently based on their intended uses. FontShop offers font licensing (that's what you're actually paying for) for normal desktop use, webfonts for self-hosting (marked with the suffix Web), and embeddable fonts for eBooks, apps, games, and certain specialty documents like editable PDFs. (This last category is a newer one, marked with the suffix App+ or eText, or it simply requires a special license.) Each foundry license (or end user license agreement) places certain permissions and restrictions on the fonts you download, so that's the source we look to when answering questions about what a given font license permits.
If at checkout you don't find the format, features, platform, period of time, or number of users you're looking for in a standard license, please write or call us during business hours and we'll work with the foundry in question to put together a custom quote.
What's the difference between Basic, Std (Standard), OT (OpenType), and Pro packages? It's primarily glyph support, mostly meaning language support, but also in features such as small caps and multiple figure sets (tabular or proportional, lining or oldstyle, super/subscript, fractions, etc.). The term Basic is also used to describe pared-down family packages that contain only the most essential weights (Regular, Italic, Bold, etc.).
Not all but most fonts can be licensed individually if you don't need the whole family, or if a smaller package is still too much.
What are Offc (Office) and Com (Communcation) fonts? These versions from FontFont and Linotype respectively cater to regular office use in programs like Word, Excel, and PowerPoint, rather than professional design apps like InDesign or Illustrator.
What about all these other abbreviations I keep seeing? Yves Peters put together a nearly exhaustive guide that walks through and explains the rest of them.