The tier benefit is access to "Emirates Lounges" in Dubai and partner lounges at outstations. The T2 lounge is presumably neither. I wouldn't be surprised if longer term they expand the lounge and do add this benefit however.

For bus boarding on EK one doesn't get to use the J bus on the basis of status. You can proceed past the initial BP check to the busses but then embark on to a regular Y bus, gone through this many times (EK Gold) and never been offered the J Bus. So no difference there, either.

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