Generally, yes. If you are fetching data about campaign structure, including ad groups, ads, etc., that will always be up to date with the web interface. If you are using reporting to look at statistics about how your campaigns, etc. are performing, there may be some delay. Please see our article on
determining your data's freshness for more information.
Also please note that some features of the AdWords web interface are not supported by the API, and will not be returned by the API. Anything using the shared library in the web interface will not be returned by the API.