While the Small Cell Forum defines the different types of Small cells clearly and these Small Cells can be said to contain the complete/partial functionality of the eNodeB, 3GPP definitions of Small Cells can be a bit fuzzy sometimes.
Generally, in the 3GPP documentation, there is a reference to Femtocells and Picocells. Femtocells are Small Cells that are defined as Closed Access (see my old post here) by 3GPP. The open access small cells are referred to as Picocells. Sometimes remote radio heads (RRH's) are also referred to as Small cells, open access type.
Relays, even though not referred to as Small Cells by 3GPP, is also referred to as Small Cells by some people.
Do you know of anything else?