The languages have a good share of common vocabulary, some words are however either pronunced totally different but written similarly or are written totally different but pronunced similarly. The word order in most cases is similar, i'm no native, but except for one scenario that involves 2 verbs i have not noticed any other word order change. Even though they have many common components, the languages aren't mutually intangible too a high degree, not even to a medium degree actually. There are just certain basic situations where they are (and those are mostly writting related)

Regarding them individually,

Dutch - has easier grammar, no cases, however harder verb conjugation (at least that's how i find it), and definitely a harder pronunciation

German - harder grammar, mostly because cases, but i also notice they seem to use more variation in prepositions, while Dutch seems simplified, pronunciation is fairly easier, verb conjugation is also easier than in Dutch

Amazing comments everybody and thanks for your time, i Was wondering because i know some Germán, and im Willing to learn dutch, but i cant pronounce ANYTHING ???? i just can pronounce "dag, hoi, tot ziens" and thats all, in Germán the pronunciation is easirer at least for me, and also the verbs conjugations in dutch is so hard makes me wanna cry, Thank You very much to everybody ☺️

Hello Lia,

Good question and everyone here already gave great answers so I just tell you about my experiences. 

I am Dutch and had to learn German in highschool. It was a completely foreign language to me. I had difficulty with the grammar and only learned to speak it by travelling once a year to Switzerland. I still can't write it. 

But if it's your third language, hopefully it will help you that you know German, although Dutch vocab and pronunciation are very different from German vocab and pronunciation. Let us know in a while if it was a benefit to know German first.

Hi Lia!

As a Dutch person who knows German as well, I definitely think it helps to know German if you want to study Dutch. As Alex said, many words are written similarly while there are also loads that written very differently. (for instance, apparaat and gerat). In German there's a lot more usage of the letter Z. Word combinations like zsch, tzsch, tz barely exist in Dutch. Also the umlaut sign and scharp S sign (the B-shaped one) do not exist in Dutch. 
I don't think Dutch grammar is easier however. In Dutch you don't have that many rules about prepositions and articles (there are only 3 in Dutch! :D), but in German those rules make it very clear which articles and prepositions to use. To know which Dutch article to you, there are barely rules and many exceptions. Dutch pronounciation may be a bit more tough, especially with the famous G. 
I'd be happy to help with understanding these things though! Message me if you're interest!

Netherlands dialects are essentially the same language as the German dialects in Northern Germany. North-Germans study "Hochdeutsch" (which is in fact a foreign language) in school, and are then generally considered "native speakers" of German, even though their native dialect is in fact a form of Netherlandish (I don't know if that's a real word in English, but it's much more accurate than "Dutch"). Old English was originally a Netherlands dialect from what is now the German side of the Netherlands / Germany border. Old English was nearly identical to Netherlandish before the Norman French invasion.

Nowadays, English, "Dutch" and "German" are not mutually intelligible, but knowing one makes it easy to learn the others. I know English and German (Hochdeutsch) quite well, so I find "Dutch" easy to read, although I can't understand it when spoken. On the other hand, I've never studied "Dutch" -- I imagine if I cared to, I could familiarize myself with the pronunciation, memorize a phrasebook and be fluent in the time it takes to fly to Holland. Of course, people would be looking at me funny on the flight. In fact, I can't remember meeting any Dutchman in the last twenty years, and a lot of them speak perfect English, German, or French, so it would be more of an academic exercise.