Interesting to hear all the varied views about the various oven you need to learn to clean. From my experience, the main differences are make (brand name), Gas or Electric, Dual Fuel, Free Standing or Fitted. Now if you pull one fitted down they are more than likely the same, if you pull one free standing down they are more than likely the same. Now be careful when it comes to the electrical wires, dual fuel machines sometimes have two plugs or spurs or one plug and one spur, carry extra 3 and 5AMP fuses. Switch off before stripping.
Hoods, well again they vary, but what can you do apart from grease and filter change? I do industrial and residential kitchen cleaning and I know for a fact you don't need 5 days training for £2000 to clean domestic ovens. I know people cleaning ovens using dip tank with dish washer tablets not green chemicals or expensive chemicals and they are getting the results.
Basically I could go on and on, but a two day course is all that is needed and a dip tank. £250.00 + an IICRC 160 questions exam (what a waste)