In WW 1, air raids were "token" attacks rather than a serious campaign. They could penetrate only a short distance into England, and the slow, hydrogen-filled Zeppelin was a death-trap for its crew. The "Gotha" bomber was rather more effective - and a warning of "the shape of things to come."
In WW 2, the Luftwaffe was never designed or equipped for large-scale bombing of cities, its primary purpose being short-range close support for the armoured columns in a "Blitzkrei" The most important of the British Air Raid Defence systems, the chain of Radar Stations along the South-East Coast, should have been "sitting ducks" for the Junkers 87 dive-bombers, but the range was too great, and the slow and almost unarmed aircraft were easy prey for the local RAF Fighters. The Stations were never destroyed, and played THE most importan part in the "Battle of Britain".
The small, twin-engned Heinkel 111, Dornier 17, and Junkers 88 aircraft carried relatively small bomb-loads, and their crews were neither trained nor equipped for the night operations which became necessary.
As a result, the German raids of 1940/41/42, though they caused great devastation in some areas - London, Bristol, Plymouth, Coventry, Hull etc. (as a member of the Bristol Home Guard, I had an overall view of the "Good Friday Raid" in 1941 - I was guarding a large unexploded bomb in a garden in Clifton ! ) - were mere pin-pricks in comparison to the Allied retaliation which followed.
As early as 1917, the RAF had decided that its most effective operations would be against enemy industrial cities - especially in "de-housing" the civilian workers, and it had been deveolping large, long-range, heavy-load-carrying aircraft for that purpose, culminating in the 4-engined "Lancaster" - THE "baby-burner" in the 1000-bomber attacks on German cities.The only 4-engined aircraft developed by the Luftwaffe was the "Condor", and that for reconaissance purposes over the sea.