getAllSections but not these specific sections
Here's how I've gone about that in the past.

Loop through all sections, and only if section.type is structure and doesn't have the handle 'pages' (skip that section, essentially);

{% for section in craft.sections.getAllSections() if section.type == 'structure' and section.handle != 'pages' %}
  What you want to do here... Print the content or whatnot.
{% endfor %}


And if you only want to get channels;

{% for section in craft.sections.getAllSections() if section.type == 'channel' %}
  What you want to do with the channels here...
{% endfor %}