Lightroom CC export setting and file size

[abcde71313152]

Hi, i'm using Lightroom Classic now and plan to change it as Lightroom CC. I already know they have some differences but i still curious about result (image quality)

When i choose image quality "100" and sRGB option in Classic Ver, it gives me original size(pixel) and 240 DPI JPEG file. and i understand it is highest quality with sRGB space. And also when i choose "full-size" in CC Ver, it also gives me original size(pixel) and 240 DPI JPEG file with sRGB space same as classic ver. As far as i understand, each image that has same size(pixel) and same resolution (DPI) should have identical size (volume). But i found that image exported from CC has 20~30%  smaller volume than Classic Ver.

My question is

- Is there any factor affect image quality that i did not catch up ?

- If image quality is exactly same, why image from image from CC has smaller size(volume)?

Thanks.

[Theresa J · Accepted solution]

Lightroom is probably applying some amount of jpeg compression although it doesn’t offer the ability to control that. Classic gives you the option to say how much, if any jpeg compression should be used.