Internally they are all pretty samey as well with the odd difference here and there such as the name on the front or an extra control knob that you will never use or a few lights or maybe a solenoid to turn the water on/off instead of a valve. ie. a few subtle differences to justify ripping you off.
Heres an example or two
I was looking at the
Wickes catalogue the other day and there were 3 showers all 10.5 kw One had a basic control. The next had the extra control knob which would never be used and the other had all the flashy lights and solenoid which is only something extra to go wrong.
The prices were roughly £60, £90 and £130 respectively aimed at the three market levels that most manufacturers seem to be aiming at these days. namely paupers [and local authorities], middle class, and filthy stinkin rich with money to throw away. Well here is the news. There is every chance that they will all have the same heating unit in them. Call me a pauper if you like but I know which one I would buy. I would want a 10.5 kw shower and for another seventy quid they could keep the solenoid and pretty LED's. BTW they are all rebadged Tritons
As it happens I am quite happy with my 8.5kw mainly cos it works and also I can't be arsed running a 10mm cable and all the other crap. If it ever goes I will be off to Newey and Eyre for their £43 managers special Newlec 8.5kw which used to have Redring parts in but now I'm told it's Heatrae Sadia.
There's loads of these 2, 3 and more tier marketing scams about. The ones I know of that come to mind are
Audi Volkswagen and Skoda
Baxi Potterton and Main
M&S Crisps KP and most of the shops own brands.
etc etc
Now thats just my opinion but do you want the pretty lights and buttons or just a shower?
EDIT :-
Just had a look
HERE Turns out that Redring and Creda are the same!
! Some of us old fogies still have outdated notions about helping our fellow humans. 
