instance_of?メソッド
"aaa".instance_of? String => true
"aaa".instance_of? Object => false
String === "aaa" => true
Object === "aaa" => true
"aaa" === "aaa" => true
String === String => false
String === Object => false
"aaa".instance_of? String => true
"aaa".instance_of? Object => false
String === "aaa" => true
Object === "aaa" => true
"aaa" === "aaa" => true
String === String => false
String === Object => false