Disk tools confusion: dd or cat or cp?

[OrsoBruno]

@F_style

I was also wondering if I could use dd to rip ISO images from physical CDs/DVDs, and found this page.
Certainly I didn’t expect this: it seems that, if using dd with just the default values, dd will add some couple of blocks for free to the output ISO file, thus checksum will not match the original CD/DVD source? Will this actually make the output ISO unbootable or uninstallable?
And, even if “correctly” ripping ISO image with dd, is there difference in the process between dd itself and common burning software such as K3b and Brasero?

As I understand it, adding a couple of zero blocks at the end of the image will not prevent booting or installing the copy made from that image; after all, no USB stick exactly matches the size of a disk, so there is always plenty of zero blocks at the end of a stick anyway.
I never recall using K3b and seldom use Brasero these days, but when I had to duplicate a physical disk I did just that (insert the master, copy, insert the blank DVDs and make copies) without any attempt at “ripping”.
For hassle-free burning to USB sticks I use the SUSE Studio Imagewriter openSUSE Software which is guaranteed not to mess with the hybrid openSUSE images BTW.