The CD4069 parts that are for sale these days always have a U after the number, that is CD4069U and this is important. This indicates that it is an UNBUFFERED gate/inverter, which is different than the CD4009. Here is a link that explains the difference:
https://www.electro-tech-online.com/custompdfs/2009/08/scha004-1.pdf
It is possible to buy "U" versions of 4009's and other logic parts as well, but they would be marked as 4009U in that case, and then I don't think there would be much difference with a 4069U in that case.
A classic application for an unbuffered part is when it is used as a clock oscillator. In this case the shorter propagation delay through the part, and slightly less complex transfer function means it oscillates at higher frequency and more reliably.