The following information was posted in cadence forum.
Both HSpice and Spectre are circuit simulators. Hspice is from Synopsys; spectre is from cadence. For each simulator, there are two interfaces. There is hspiceD and hspiceS (hspice Direct, and hspice Socket), and spectre and spectreS (spectre Direct, and spectre Socket).
The socket interfaces are the obsolete interfaces to the simulators. The hspiceD and spectre interfaces are the ones to go for. Hspice is a perfectly capable simulator for noise.
The following manuals are gathered from different sources. You can use them for references when you want to use hspice to do simulations in Cadence.