We investigate experimentally and numerically the turbulent natural convection flow that develops in a differentially heated cavity of height H = 1, width W = H and depth D = 0.32H, submitted to a temperature difference between the active vertical walls equal to 15 K resulting in a characteristic Rayleigh number equal to 1.5 x109. In the experiment temperature is measured by 25 µm micro-thermocouples and velocity by a laser Doppler Anemometer. BNoth 2D and 3D LES and 3D DNS are performed. DNS uses a Chebyshev spectral method and LES a finite volume method with a local subgrid diffusivity model. Numerical simulations are performed for both adiabatic conditions and experimentally measured temperature on the horizontal walls. Time-averaged quantities and turbulent statistics in the median vertical plane are presented and compared.