IDM: Identity?

I agree. Accounts do not equal Identities in the multi-platform, cross-vendor world we live in. This and various other terms (roles, profiles etc) that have different meanings on different platforms often create confusion when I've had IAM discussions. But then, it all depends on how you define Accounts and Identities.

Three words, smashed into one: OpenID

From someone that is in SIEM and IAM - yes, these are not synonyms: user, logon, account, identity, ID, username. Unfortunately, they mean different things to different vendors. I make sure that I spend plenty of time making the customer knows what I mean.