A little funny that a metadata field is labeled “EPD program” as I believe that what we’re seeing there is a ‘unit process’ and not an EPD. I don’t know OneClick, but have used ecoinvent for LCA. If my description below doesn’t apply to OneClick for some reason, I’m happy to stand corrected!
A unit process is the smallest unit in a life cycle inventory (LCI, the process model behind a life cycle assessment) and will describe a process of material transformation. In a unit process, the inputs are raw and processed materials. The outputs are the ‘reference product’ (for which the process is typically named), emissions to air/water/etc., and any co-products. These inputs and outputs describe physical/energetic flows, so there’s no GWP directly attached to a unit process.
In the life cycle impact assessment (LCIA) phase of an LCA, all of the physical flows from the LCI are assigned to ‘midpoint categories’ (like GWP or ODP) using a set of characterization factors (like those provided by the EPA or IPCC, for instance).
tl;dr - An EPD describes the results of an entire LCA and reported as environmental impacts, a unit process is a teensy part of an life cycle inventory and reported as a set of physical/energetic flows. Ecoinvent is a collection of the latter.