To my colleagues who are familiar with Sentinel-2 data Are these data geometrically corrected ?? or need to be georeferenced as an image to image? what the best software for processing??
That depends what processing level you are referring to. Most data is delivered as Level-1C. According to the Sentinel-2 documentation:
Level-1C product provides orthorectified Top-Of-Atmosphere (TOA) reflectance, with sub-pixel multispectral registration. Cloud and land/water masks are included in the product.
Level-0, 1A and 1B are not directly disseminated to users but for completeness:
Level-0 is compressed raw data. The Level-0 product contains all the information required to generate the Level-1 (and upper) product levels.
Level-1A is uncompressed raw data with spectral bands coarsely coregistered and ancillary data appended.
Level-1B data is radiometrically corrected radiance data. The physical geometric model is refined using available ground control points and appended to the product, but not applied.