How NOT to Summon a Demon Lord( Isekai Maou to Shoukan Shoujo no Dorei Majutsu) Light Novel Vs. Manga
Is reading the manga the same as reading the light novel?
Having not read the manga myself, I can't answer with any certainty. In general though, a novel contains much more detail than a manga does.
No. It's not. The light novel has a lot more story to it that the manga does. While the manga gives you a visual aspect to entertain you, and that's not a bad thing by any means, the light novel goes a lot more into depth with the story itself so if you've only read the manga and been wondering "how did we get from here tho here" in the story, that part is most likely in the light novel, but was cut out for expediency to move the story along.
So, basically, if you want to get the entire story you need to read the light novel. Me personally, I find the light novel to be more entertaining and it helps me to enjoy the manga more once I read it. But that's just me.