About hash notation (there are two ways to get values for keys: hoge[:title] and hoge.title)

When I deal with values from json, I always get confused because I don't know which of the following two patterns.

hoge [:title]
hoge.title

< Assume that the value of the key is obtained

Handling hash when parsing Json

hoge=resp.body.map { | hoge | JSON.parse(hoge)}

OK.
hoge[0].title

NG
hoge [0] ["title" ]

On the other hand, when you put a hash into a variable? is

hoge={:id=>"123",:title=>"test"}

OK.
hoge ["title" ]

NG
hoge.title

I thought the behavior was different depending on whether it was included in the variable or not, but
I asked you a question because I didn't come across the literature explaining it in pinpoint.

Also, I sometimes wonder how find behaves in hash.
I would appreciate it if you could let me know if there are any URLs that I can refer to.

Thank you for your cooperation.