Standards is often used in the sense of "padrão de qualidade", that is, when it have to do with quality. Or other "padrão" of something, for example "standard of living..."
See some sentences:http://sentence.yourdictionary.com/standard
Pattern seems like varying more, please see:http://sentence.yourdictionary.com/pattern
It might have the sense of "padrão/modelo/motivo (figuras, em moda etc)/modelo/desenho/amostra/algo típico de, ou usual - característico/perfil etc.
And it might even mean "padrão" in the same sense of the above "standard".
Practice makes perfect, so you may craw within the http://sentence.yourdictionary.com/
and the Linguee, to get the hang of it.