The answer is yes and no. There are 2 types of product at the moment. One will give you a fixed maximum downstream speed e.g. 2 Mb/sec and the other is an adaptive rate system, often called Max, which will offer up to 8 Mb/sec depending on your line length, condition, etc.
Orange is offering you a fixed speed package, Waitrose is offering you a Max package with an estimated speed of 5 Mb/sec.