I've looked around a good bit to see if I could solve this problem on my own. I've managed to get close I believe, but I think I don't quite understand Craft's relationships.
Basically, I have a related projects section on my site. I'm allowing the user to select the related projects with an Entries tag within my matrix. I would then like to compare their selected Entries with projects already added to a Structure - then output attributes that exist only in the Structure.
This is as far as I've gotten:
My Structure Content
{% for entry in craft.entries.section('homePageBanners').limit(3) %}
{% for block in entry.banner.limit(3) %}
{{ block.client }}
{{ block.bannerImage }}
{% endfor %}
{% endfor %}
My Matrix Entries Block:
{% for entry in block.projectsEntry %}
<a href="{{ entry.getUrl() }}">{{ entry.title }}</a>
{% endfor %}
I'm not sure how to compare them & pull content based on what the user selects. I looked into relatedTo(), but didn't have much luck with that.
If that's not clear, I can try to be more specific -- please go easy on me, I'm pretty new to Craft.
EDIT:
Maybe this will help clarify {% for entry in block.projectsEntry %}
{% for project in craft.entries.section('homePageBanners').limit(3) %}
{% set relatedProjects = craft.entries.section('homePageBanners').relatedTo(project) %}
{% for project in relatedProjects %}
<a href="{{ project[0].getUrl() }}">{{ project[0].title }}</a>
{% endfor %}
{% endfor %}
{% endfor %}