Usually 'no' is more emphatic than 'without', but in a specific way.
'This cake is made without sugar'. - Saying 'without' means that something *shouldn't* be there.
'This cake is made with no sugar'. - This stresses the *positive* absence of something, i.e. the lack of sugar in the lack is implied to be a good thing.
That said, 'without' is the more common structure, so when in doubt, say 'without'. I apologise for the inadvertent rhyme.
That said, there are certain turns of phrase where 'without' is stronger. 'Without doubt' is used to express absolute certainty about an opinion, and 'no doubt' is just being very certain about an opinon.