Two Baltis. Could they be any more different? There are still similarities though!
Here are 2 "Balti" dish videoes, I watched this morning. They are not the same dish (one is Chicken Tikka and the other is Chicken & Spinach) but they are both claimed to be Balti.
The Birmingham Balti cooks the chicken from raw again, while the BIR uses pre-cooked (it's Tikka so can't be avoided really). I think the different approaches taken by the chefs is important as it clearly demonstrates the differences between Birmingham and BIR (to me anyway). There are some very informative moments in the commentary of both.
The first one is a follow on from the Misty Ricardo and Andy Munro visit to the kitchen of Shababs and again cooked by Chef Zaf. This looks like a really nice curry.
https://www.youtube.com/watch?v=8H77IzOvx04An interesting thing here is the quantity of Paprika used. If I used 1 TBSP of my Indian Paprika (which is 4 tsp or even UK 3 tsp) it would be way too hot so I must assume it is only Sweet Paprika, but then there is only 1 green chilli added otherwise. I have nothing to go on as a guide to how this should be regarding chilli heat. This clearly shows the use of his restaurant version of Base Gravy, which his cook from scratch Chicken Balti did not. There is no full description of exactly how the pre-cooked spinach is done so it's a stab in the dark to try to replicate this, but I think you could get pretty close to what is supposed to be the real Shababs Birmingham Chicken & Spinach Balti if you use Misty Ricardo's version of the Shababs Base Gravy and some form of Indian pre-cooked spinach. I'll definitely be giving this a try and I have one serving of base gravy left.
The second Balti is demonstrated by Latif and there are 2 interesting things in this Chicken Tikka Balti.
https://www.youtube.com/watch?v=WZLFHYpHsuQHe clearly states that when it comes to adding the spices, he would normally use his mixed powder. Instead he breaks it down and uses stated quantities of single spice powders. This could be his 5 spice Mixed Powder.

He uses Balti paste. Yes indeed, and he shows a big bottle of commercial Patak's Balti Paste, but he then says he makes his own using yogurt and spices (undisclosed) and uses this in the dish instead. We don't know what this is and using different paste will obviously give different results. Anyway, I'll need to fire up the tandoor to cook a bit of Tikka to try this one out.
There are of course many similarities in ingredients, but perhaps not the quantities used (eg; capsicum) but to me these 2 dishes illustrate the difference between the Birmingham Balti and the BIR Balti.