Hmm. You're right that we often use those terms interchangeably. Technically, the driver is the piece of code that runs in the operating system kernel that does the low-level programming of the I/O hardware.
This low-level programming is somewhat complicated, so we create a higher-level Application Programming Interface (API) on top of it that is more natural for the user's programming environment. So, for example, NI-DAQmx has a driver that controls NI's DAQ hardware. NI-DAQmx also includes a LabVIEW API for LabVIEW users, a C API for CVI users, etc. So when we talk about NI-DAQmx in LabVIEW, we're talking about the whole stack of software--the LabVIEW VIs for DAQmx all the way down to the low-level kernel driver. Sometimes we call it the NI-DAQmx driver, and sometimes we call it the API. For the most part, you don't ever have to care about which specific components we're talking about. The same is true for all of these other products you mention. For example, NI-SCOPE is the software you use to talk to NI's Oscilloscope products. It includes an API for LabVIEW, an API for C, as well as the low-level driver that programs the hardware. Does this help clarify things? Brian
