Galatians 5:19 - Now the works of the flesh are evident, which are: adultery, fornication, uncleanness, lewdness, 20 idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies, 21 envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand, just as I also told you in time past, that those who practice such things will not inherit the kingdom of God.
In 1 Corinthians 6:9, Paul refers to such people as the unrighteous who will not inherit the kingdom of God and mentions a similar list of sins in vs. 10, but then goes on to say in verse 11 - And such were some of you. But you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus and by the Spirit of our God.
It is the lifestyle, or pattern of this behavior being exibited in one's life. To stumble and sin intermittently is different than making these behaviors a lifestyle. The idea of "practice" is to perform repeatedly or habitually and thus describes repetition or continuous action. Paul uses the present tense which describes the practice as habitual, as one's lifestyle or bent of life. Those who practice such sins demonstrate they have not been born of God.
There is certainly a difference between "practice" sin (no repentance, just bring it on!) and commit an act of sin but continue to pursue practicing righteousness in keeping with repentance.