On some things where the Quran and Sunnah are silent, and it becomes evident that these things are impure and unsuitable for the believers in light of the guidance of the Quran and Sunnah; the scholars have termed such things Makrooh or disliked. Example being cigarettes, etc.
Everything that is declared Haraam by Allah and His Messenger (saws) are also disliked, and thus every Haraam thing will also be considered Makrooh; but not all makrooh things will necessarily be considered Haraam.
Sahih Al-Bukhari Hadith 3.267 Narrated by An Numan bin Bashir
The Prophet (saws) said "Both, halaal and haraam things are obvious, and in between them are (suspicious) doubtful matters. So whoever forsakes those doubtful things lest he may commit a sin, will definitely avoid what is clearly illegal; and whoever indulges in these (suspicious) doubtful things bravely, is likely to commit what is clearly illegal. Sins are Allah's Hima (i.e. private pasture) and whoever pastures (his sheep) near it, is likely to get in it at any moment."