Distribuição específica não tem mais diferença. Havia alguns drivers de código fechado no pacote não-OSE, mas eles foram movidos para um pacote extra.
Before version 4.0, there were two editions of VirtualBox: a full binary containing all features and an "Open Source Edition" (OSE) with source code. With version 4.0, there is only one version any more, which is open source, and the closed-source components have been moved to a separate extension pack. https://www.virtualbox.org/wiki/Editions