I have looked into commentaries and word helps, but it is very unclear to me what the scripture teaches about these issues.
A review of Webster’s New World Dictionary, W.E. Vine’s Dictionary of New Testament Words and the New Bible Dictionary, reveals the following:
Sanctification — to set apart as holy; to make free from sin; separation to God; set apart.
Justification — to free from blame; to declare guiltless; pronounce righteous; declare righteous.
Both words are used several times in the Bible and one time in the same verse, (I Cor. 6:11). My conclusion is that while there are some differences between the two words, they are closely related.
It seems that one is justified by having his sins removed and becoming righteous, and then he/she is sanctified, or set apart, to serve God the way His word directs.