Dutch doesn't have the same intonation, has harsher pronunciations, and has a whole extra sound most English people struggle with (a rolled r).
The older generations also can't pronounce -thew very well as it's not a thing in Dutch, so struggle to pronounce my name, calling me Matchoo instead of Matthew. It still boggles my mind that my Mum would pick a name the Dutch can't pronounce.
The Dutch accent is also extremely noticeable to a native English speaker.
Ultimately, they're not the same at all as English is Germanic/Latin hybrid where half the words are French/Italian words, and half the words are Germanic/Dutch words.
Dutch is not.
You can usually tell by looking at the word and the end of the word.
Words like fantastic, manual, vision, aquatic, consume are all from -ique, -alle, -umme and will have similar words in French/Italian. The tend to be longer words with more syllables.
Words like mother, strong, good, are Germanic in root. The -er, -ong, -od words will all be similar to the German/Dutch words. Shorter, quicker to pronounce.
Maybe she meant for you to go by Mathias (or whatever the local equivalent is) when in the Netherlands?
https://knowyourmeme.com/memes/english-to-dutch-translations
The connection between Dutch and English languages is far more minimal in comparison. In fact, when I first faced the language, I would have said it was a combination of ~80% German, 10% English, 5% French, +5% Others.
> In fact, when I first faced the language, I would have said it was a combination of ~80% German, 10% English, 5% French, +5% Others.
But the vocabulary of English itself is majority of Germanic origin. So while Dutch is often closer to the modern German, there's definitely far more than 10% that has a common origin with English as well as German.