Between TunesKit Video Cutter and FameRing Smart Cutter, which is the better, more reliable lossless video cutter for MPEG2 .ts video?

Are they both really lossless? Because when I cut out the same portion of a video with both software, the size differs by 10-30mb between the two outputs. FameRing Smart Cutter output the video a lot faster but it's usually smaller file size compared to Tuneskit Video Cutter's output.

ps: for Smart Cutter, I have 'whole gop mode' checked so the start and end won't be re-encoded.