I am thinking of a particular word property.
'Aluminosilicates' has this property, but 'unprosperousness' does not.
'Epicoracohumeraler' has it, but 'conversationalists' does not.
'Honorificabilitudinitatibus' does, but 'antidisestablishmentarianism' does not.
What property am I talking about?
In the word "Alluminosilicates" there is NO incidence of the occurrence of two consecutive vowels or two consecutive consonants.
However, "unprosperousness" contains two consecutive vowels "ou" and two consecutive consonants like "np", "pr", "ss" etc.
The other two pair of words can easily be checked to confirm that they indeed have this property.
Consequently, each of the bolded words does not contain two vowels or two consecutive consonants. However the non-bolded words does not follow this rule.