DUI vs DWI Texas laws differ based on age and impairment. DUI (Driving Under the Influence) applies to drivers under 21 with any detectable amount of alcohol and is a Class C misdemeanor. DWI (Driving While Intoxicated) applies to minors and adults and can involve alcohol, drugs, or prescription medication, including a BAC of 0.08% or higher. Both offenses carry serious penalties under Texas law.