Edit: I also nearly witnessed a "carpetbagger" situation at a local credit union (where leadership wanted to become a bank/corporation), which was voted down.
Yes, the credit union is very similar in practice, although there are numerous technical differences. The most obvious practical difference was that originally Building Societies were oriented around this idea particularly of loans for members to buy homes, a worthy goal that is also conveniently economically sound. Credit unions are broader in scope from the outset.
It was perhaps more obvious (especially for the Limited Building Societies) that they've achieved something good if now everybody owns a home, whereas if now everybody has a savings account with the credit union, er... is that better? Maybe?
Edit: I also nearly witnessed a "carpetbagger" situation at a local credit union (where leadership wanted to become a bank/corporation), which was voted down.