The rights referred to in the declaration go beyond the 'freedom and security' you've mentioned in your post.
For example, in Canada it gives the Métis and Inuit peoples, along with the First Nation tribes (such as the Cree and the Iroquois) the right to have their native languages respected and, importantly, to ensure that their children receive their tuition at school in those languages, rather than in English or French. It's akin to the right of Welsh people to have their children taught in Welsh.
The full text of the Declaration explains far more than I can though:
http://www.un.org/esa/socdev/unpfii/documents/DRIPS_en.pdf
'Equality' isn't synonymous with 'homogeneity'.