Is it true to say that CTRL+D stops input execution while CTRL+C stops output displaying (as plain data, without execution)?
No, it is not true.
However, it is true to say that Ctrl+D signals an End of Transmission (EOT) event which will generally cause a program reading input to close the input file descriptor.
Ctrl+D is used for this because its place on the ASCII table corresponds to the analogous End of File control character, even though the actual EOF control character is not actually transmitted in this case.
Pressing Ctrl+C will generally (it's configurable with
stty) generate an interrupt signal (SIGINT) which will be delivered to the processes that are in the current terminal (see
man 3 tcgetpgrp).