On computers:-
Sometimes one font will be used for katakana and a different one for kanji. When this happens you can often differentiate them. This often happens on the internet due to browser settings or website designers not setting suitable font, where sometimes a Japanese font gets used for kana but a Chinese font ends up getting used for kanji (causing other character problems).
Even when the same font is used for both, like here on JCJP which uses the Japanese font "Meiryo", you can still see very slight differences for all three of those characters.
But, for computers at least, there is a very simple way to determine for definite whether a character is kanji or kana or something else. Just copy-paste the character into the search box on the following unicode codepoint lookup website:
http://unicode.scarfboy.comOctober 3, 2016 at 2:52am