I would guess he's coming from the standpoint of using software that (always) "renders". When I was new to this,
Sony Vegas and Camtasia or other like software offered no simple option like (save to disk) you always had to "publish" or "render" or "upload" to Youtube after editing source clips together.
So the OP may be asking if saving to lossless or other any other method is "truly" like saving a file, or asking if is really only a different form of "render". It messes with your head after unlearning there is "no lossless" save to file option from most editing programs.
If that is the case..
Then the answer is complicated.
First (yes) when we say save to "lossless" we really mean save your file as a bit for bit identical copy of your edit stream.
The difference is we are talking about clips that are not compressed at all.. they are really uncompressed frames on the edit stream, when they are saved to disk, they are saved exactly as they are.. only they are compressed "losslessly" which is more akin to saving the uncompressed stream to a file, then running zip or winrar on the result so the uncompressed file gets smaller.. but looses no detail. That's why its called "lossless". The
Huffyuv or Lagarith "codec" is not really compressing the bits within the frames, but the frames themselves after the fact.. when they are uncompressed (file is opened) then they are restored to their exact original condition with no losses at all.
Editing Uncompressed video is not like editing Compressed video. Once the clips are put together there is no "discontinuity" between groups of frames that share bits between frames.. so you do not have to "sync" them up as it were. Its more like cutting full frames of movie film together.. there is no reconciliation between the clips during "render" to recompress the stream so that it plays back smoothly on a lower power decoder program or decoder device.
Normally if your edited Compressed stream of clips were just smushed together into a stream and saved, then tried to play that back on a program or device it would "choke" the stream would not be in a form that the decoder could smoothly process.
This trade off.. is why most Compressed (aka most video Editors) must "Recompressed" or "Re-encode" or "Render" a stream of clips of Compressed video.. to smooth out the transitions and fixup various things like indexing depending on the output type of the video file.
Uncompressed editing doesn't need any of that, its ready to be played back immediately, so it can be saved straight to a file. then you can run zip on it or winrar to compress that file "losslessly" (or) you can choose to "render" (miss-use of the term) in some editors using the
Huffyuv or Lagarith "codec" to a lossless output file.
It gets complicated where some editors can't use the "lossless" codecs, or they have alternatives like Apple ProRes which are not quite lossless, but along the same ideas.. that is.. a codec that is intended for "editing" that retains as much detail as possible, even when re-encoded.. until such time as you render to a "publication" type like DVD compliant MPEG2-PS or other formats.
The long story is that computers have not been practically capable of capturing, editing and saving in Uncompressed format until relatively recently, it was simply astronomically expensive and even TV and Movie studios (Professionals) used Compressed capture, edit and save of their projects.
That has rapidly changed in the last ten years.. and people can now reach for much better capture output and do ("amazing") things with very poor video.. as long as its captured in Uncompressed format. But Uncompressed format normally eats disk space rapidly and one hour of video is Gigantic in size. To help with this Huffyuv and Lagarith were created and compress the "frames" losslessly on the fly during capture and make the Gigantic files smaller.. while still making them editable in many popular video Editor programs.
When you edit Uncompressed clips together and save back to disk, those frames are not "rendered" they are literally "transformed" 100 percent as they originally were into a compressed "zip file" like format which is smaller.. but retains all the resolution and details of the original video. When you re-open those "lossless" files in a video editor, they come back 100 percent as they were when they were put into the "lossless" codec for saving to a file (even if the program says its is "rendering" them.. which in this context means its only "saving them").