Use of Bestimmt or Sicher?

In lesson 2.2 "On a Tour", the conversation ends with "Bestimmt" translated to "For Sure" - but when I used that in reply to my German colleague when he was asking if I can do something for him, he said I should say "Ja, Sicher" and not Bestimmt.

Can anyone explain when one is used over the other please?

Danke!

Hi Darren,

In many cases they can be used interchangeably particularly when used as an adverb to mean: certainly, definitely, of course, for sure, surely.  Used as an adjective they are still pretty close but there are some nuances.  Sicher has a connotation of safety or security whereas bestimmt can mean fixed, definite, certain,set, particular.

Like English, German has many synonyms. 

Hi Darren,

It really depends on the context. "Bestimmt" For sure" was the the answer to the question "Gibt es dort Toiletten?Are there toilets?"  Bestimmt doesn't mean the person knows for a fact that there are toilets but believes that there will be some. If your colleague asks you if you can do some work for him than "bestimmt" is a good answer but "sicher" expresses 100% certainty about it. 

Regards

Olga

OK thanks for that. He understood what I meant but I like to learn how the natives may say it. I'm in Celle, Germany at the moment and it's amazing how many signs and words you hear that you pick up from the course. (I'm only on Lesson 2.4!). I also showed Rocket German to my German colleague and he was impressed with the accuracy and testing section and said I pronounced words fine, which I'd learnt from this course! Very pleased and motivational to carry on, to say the least.

It's great to hear Darren. Good you're getting the chance everyday to practice what you've learned here.