Compared with landsat 8

I need to compare the images landsat8 missions and sentinel 2 missions from the same period of time. how I used the code landsat8 mission surface reflectance factor of 0.0001 if anyone can tell me what is the surface reflectance factor in sentinel 2?

Actually there is no factor for the conversion to surface reflectance.
But there is a factor to TOA reflectance. See my post here
And for landsat8 I don’t know, but I don’t think that there is constant factor.
And I think these are also TOA radiance or TOA reflectance. (see http://landsat.usgs.gov/Landsat8_Using_Product.php)
By default SNAP provides the TOA radiance but you can change to TOA reflectance by specifying a property.
To do this lookup the .snap folder in your user directory. Inside this folder create a folder named etc if not already existing. And in this folder create a file named s3tbx.properties.
To this file add the follwoing line:
s3tbx.landsat.readAs=reflectance
Afterwards the values of landsat will be TOA reflectance.