ncbi sra
 

I'm new to ncbi sra, and I think I'm not quite clear on the formats. When I download the sra files, what is the difference between filtered and non-filtered? I could only see a length difference. But when I tried to check whether one sequence present in the filtered file was also present in the unfiltered file I could not find it. Also I could neither in the filtered nor the unfiltered file recognize whether adapter sequences were still present. Are the files adapter removed?
Thanks for the help, C