Difference Between Filter Hooks: the_content vs. the_content_rss

Hi,

I am trying to understand the difference between the filter hooks the_content and the_content_rss.

I just recently modified a plugin that embeds videos so that a different embed code and/or text is used when the post is viewed as RSS (e.g. “There is a video embedded here. Please visit the original post to view it.”).

I have applied the function to the_content as well as to the_content_rss. Within the function, I try to distinguish between “normal” post and feed with is_feed().

Works fine.

I have a question, tough:

Is everything that is applied to the_content also automatically applied/passed on to the_content_rss, or are both filters handled separately? In other words: if I check for a feed via is_feed() in a function applied to the_content, do I still need to apply the function to the_content_rss? Or is the last one just another chance to add special information that shall not be seen in the post (like a copyright), but it already has the changed content of the post?

Example (for a better understanding): Imagine I apply a function that changes “and” to “or” within the_content.

Before: The Dog is grey and the cat is black.
After: The Dog is grey or the cat is black.

If I do not apply that function to the_content_rss, will it read the “and” or the “or” within the feed???

So, the main question is:
Do I really need the_content_rss for the modified plugin?

Thanks!