How can this be? Construction project house + land

You initially did not mention interest rate, initial repayment, or duration of the fixed interest period. But you need that to compare ...

For the two amounts in the first post, I assume they are the installments.

Correct

As said, without the other information, you cannot be helped.

If you have two offers, then you surely received something in writing, right?

So, once again for note-taking: loan amount €340,000, correct?
1. What is the mortgage lending value? That is, how much equity do you have, how high are the total costs of the house and land? What is your income?
2. What fixed interest period?
3. Is the interest rate the one mentioned above?
4. What initial repayment rate?
5. What is the remaining debt after the fixed interest period?
6. How long is the expected term?
7. What kind of loan is this? Annuity loan, pre-financed home savings contract, KfW included...?

Only then can one say anything about it. Why do you actually have such different installments?

Sorry, I don't want to offend you, but from the way you ask, I get the feeling that you have absolutely no idea what is being offered to you and you can't make any kind of comparison at all. So I would strongly advise you to first familiarize yourself a little with the subject before you let offers be made to you and before you sign anything. With probably the largest investment of your life, you should know what you are doing!

Thank you for writing it. When I read the first post, I thought to myself: "Where is the hidden camera?" The question contains so little information that a reasonable answer is not possible. It would be the same as if I walked into the butcher's and loudly shouted "MEAT". If the butcher is nice, he will ask me from which animal, which cut, how much I want, etc. If he is not nice, he shakes his head and ignores me. Sorry but you should tell us the points mentioned by Bauherren2014 so that we can give you a reasonable answer.

It would be just like if I walked into the butcher and loudly shouted "MEAT".
If the butcher is nice, he would ask me from which animal, which cut, how much I want, and so on. If he isn’t nice, he would shake his head and ignore me.

A very nice comparison. :-) You just put a smile on my face.

Haha very funny. Cyber financial advisors who are mistakenly so convinced of their knowledge that they are not intelligent enough to read a very simple question.

The points raised are so irrelevant to answering my question!!!!

I'll make it simple for the people who can't see the forest for the trees.

The Chiquita banana (money) costs 1€ at provider A, the same banana from the same tree, same size, same taste costs only 0.85 cents at provider B!