The studies had different methodologies and questions.
The Ipsos one asked respondents:
"Taking all things together, would you say you are: very happy, rather happy, not very happy, not happy at all?"
The World Happiness Report asks the respondents:
"think of a ladder, with the best possible life for them being a 10 and the worst possible life being a 0. They are then asked to rate their own current lives on that 0 to 10 scale."
Unsurprisingly, the two offers very different conclusions.
The Ipsos one asked respondents:
"Taking all things together, would you say you are: very happy, rather happy, not very happy, not happy at all?"
The World Happiness Report asks the respondents:
"think of a ladder, with the best possible life for them being a 10 and the worst possible life being a 0. They are then asked to rate their own current lives on that 0 to 10 scale."
Unsurprisingly, the two offers very different conclusions.