Hi Stacy,
Being honest, we could not get our different business units to use a single naming convention for their Portfolios, Programs, and Projects. We focus it on how they like to group things for reporting since you can add dashboards to Portfolios and Programs in the layout and it automatically applies the filter for you. The majority use Portfolio for Client and then Program for the key initative (normally identified in the Annual SOW). But some have business pillars/divisions that they like to do reporting on (i.e. all pharma accounts, etc.) and then use program for the specific client.
We can allow this flexibilty since we have an integration with our financial system to pull in the official client, division, product info (codes and description) and it attaches them to a custom form on a project.
I do agree that users tend not to know the difference between the Workfront icons, but I think if you set the expectation (Portfolio is client, program is type of project, or whatever works for you), your users will get that.