Smaller in file size, actually. And even smaller if CD-DVD Speed actually optimized the PNG output. Lossy compression (JPEG) is suitable for things that are naturally analog (music, photos) whereas things that are naturally digital (screenshots) are much better served by lossless compression.
And also, please do not set your CD-DVD Speed window so big! The default size for the CD-DVD Speed window should be used, not only for consistency, but also out of consideration for other forum members.