YouTube API difference between API Key and Develop

I'm having some issues understanding the differences between an API Key and a Developer's Key when it comes to utilizing the YouTube API.

My application is using the restful requests in v3 of the Youtube API and I can set an API key via the gapi.client.setApiKey() function , which I have done during development, but when I was looking at the quotas, https://groups.google.com/forum/?fromgroups=#!topic/youtube-api-gdata/e1JDQ4lqbXU, it states that they are tied to a developer key instead and that the developer key should be sent with each request. I went ahead and got one for development purposes, but I'm not sure how they interact with each other.

I also didn't find any details on how to send the developer's key with each restful request (such as gapi.client.youtube.channels.list), only how to include it in the header or query string when making a regular get request.

Can someone help me understand the difference between the two, how they are related, whether I need both, and how to use them in restful requests, or if I need to switch to regular get requests?

Sorry for the confusion.

"Developer keys" refer to keys that worked with v1 or v2 of the YouTube Data API. You can obtain them here. There's a separate quota system in place for v1/v2 and yes, developer keys do come into play there.

"API Keys" refer to keys that you use when making unauthenticated requests using v3 of the YouTube Data API. (If you're making an authenticated request, you don't include an API Key, since the OAuth 2 client id/secret identifies your application.) You get an API Key that you could use with YouTube from the Google APIs console, after turning on the YouTUbe Data API v3 as one of the Services you're using. Quota in v3 is tied to your API Console project, and your API Key identifies which project you're using.

The takeaway is that if you're making unauthenticated YouTube Data API v3 calls, you should only include an API Key from the Google APIs console in your request. If you're using the JavaClient library, that's done via gapi.client.setApiKey().