Both translate to 'this'. Isso is a coloquial form of isto. Aquilo translate to 'that'.

That sounds similar to spanish' esto, eso, aquello so I guess their usage is similar?

Esto (isto) = this (at hand's reach)

Eso (isso) = that (close but out of reach)

Aquello (aquilo) = that (far away)

Isto and isso are both "close" but they're still different degrees of closeness. I would still translate 'eso' as 'that'.

EDIT: But I guess you speak Brazilian Portuguese:

https://en.wiktionary.org/wiki/isto#Portuguese

https://en.wiktionary.org/wiki/isso#Portuguese

> isso: (demonstrative, informal, Brazil) this

Yes I speak brazilian portuguese. I think the usage is different from spanish, and probably 'isto' and 'aquilo' is the same for both in Brazil and Portugal, while 'isso' usage exists only in Brazil.