Actually I found out what the issue was.
When enabling barrel distortion correction, C1 additionally crops the image a little bit.
So, if after applying barrel distortion correction, use the crop tool to "expand" the crop area to the maximum (and centering it), I get the same as OOC jpegs and LR.
It's very tricky.
I guess they want to leave the choice of the area to keep to the user, whereas LR and OOC jpeg center the crop automatically.
When enabling barrel distortion correction, C1 additionally crops the image a little bit.
So, if after applying barrel distortion correction, use the crop tool to "expand" the crop area to the maximum (and centering it), I get the same as OOC jpegs and LR.
It's very tricky.
I guess they want to leave the choice of the area to keep to the user, whereas LR and OOC jpeg center the crop automatically.