Cost or pricing data - waiver vs exception

[Whynot]

Does a waiver to cost or pricing data indicate that the CO has made a determination that cost or pricing data is required but has obtained a waiver from the HCA?

See 15.403-1©(4) ?If the HCA has waived the requirement for submission of cost or pricing data, the contractor or higher-tier subcontractor to whom the waiver relates shall be considered as having been required to provide cost or pricing data?.

And does an exception to cost or pricing data indicate that the CO has made a determination that cost or pricing data is not required and has therefore granted an exception?

See 15.403-4(a)(1) ?The contracting officer must obtain cost or pricing data only if the contracting officer concludes that none of the exceptions in 15.403-1( applies? and ?Unless an exception applies, cost or pricing data are required??.

But exceptions to cost or pricing data include the granting of a waiver - see 15.403-1((4) ?When a waiver has been granted??.

How is granting of a waiver considered an exception ? they seem to be different; or somewhat similarly, can a waiver be granted on the basis of an exception?