Differences - benefits of using First:
Ground: Check-in at the First area at the South side of LHR Terminal 5. Minimal excitement for this.

Lounge access: Pass security, you get to turn right and use the "special door" to directly access the Concorde Room and avoid walking past half the T5 shops.

Lounge: Use the Concorde Room as your Terminal 5 lounge. Access is mainly for BA First passengers so it is exclusive. BA and OW frequent flyers use the T5 First Galleries lounge which is a separate lounge. There is a restaurant area with private booths with a comprehensive three course menu. No buffet option. You can choose to order and dine in the main lounge area as well if you wish.

Pre-book a private cabana in the Concorde Room if you wish for a more private/exclusive feeling. You can recline, watch tv, call the office, shower, eat and drink your private room.

On Board:
A more personalised service by crew
Dessert wine option (love this)
Better toilet to passenger ratio:
BA pajamas (just ask for these on day flights)
Seats are converted to full beds with sheets and duvets on request

Have I sold this yet?