Hi Ankit,
Thank you for reaching out.
Kindly refer to my response below.
1.) which advertising channel subtype can I use for each (search, display, and shopping) advertising type?
The
AdvertisingChannelSubType will depend on your preference for the campaign you are setting. Each subtype has an equivalent feature. This is an optional field for Search,
Display, and
Shopping campaigns. You may refer to the links and this
guide for more information.
2.) what are search express and display express advertising channel subtype?
These subtypes cater AdWords Express campaigns, now called
Smart campaigns.
Regards,
Dannison
Google Ads API Team

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