The difference between maniy (semen) and madhiy (prostatic fluid) in terms of their characteristics
Question

How can I differentiate between maniy (semen) and madhiy (prostatic fluid)? Is it by smell?
Praise be to Allah.There are three basic differences between semen and prostatic fluid. They are:
1.. Semen is emitted forcefully, whereas prostatic fluid is not emitted forcefully, and the individual may not feel that it is emitted.
2.. Semen is a white, thick fluid, which smells like palm tree pollen or dough, whereas prostatic fluid is a thin, clear, sticky fluid that has no smell.
3.. Emission of semen is followed by loss of desire, whereas the emission of prostatic fluid is not followed by loss of desire.
An-Nawawi said in al-Majmu‘ (2/141):
Each of these three is sufficient on its own to determine that it is semen, and it is not stipulated that all three characteristics be present. If none of these characteristics is present, then it is not semen. End quote.
It says in Fatawa al-Lajnah ad-Da’imah (4/138):
Maniy (semen) is a thick white liquid that is emitted from the penis with feelings of pleasure. After it is emitted, the individual feels tired. Semen is pure (tahir) according to the correct scholarly view, but it is recommended (mustahabb) to clean it off one’s garment by washing or scratching it. Emitting semen makes ghusl obligatory, whether it happens as a result of intercourse or a wet dream. If it is emitted without feelings of pleasure, because of sickness or intense cold, then it does not make ghusl obligatory; rather it becomes obligatory to do wudu only.
Madhiy (prostatic fluid) is thin, white and sticky. It is emitted from the penis during foreplay with one’s wife, or when thinking about sex, but it is not emitted forcefully and does not lead to tiredness. Prostatic fluid is impure (najis), and if it is emitted the individual must do wudu, wash the penis and testicles, and sprinkle water over where it got onto his body and clothes.
Wadiy is a thin, white fluid that may be emitted from the penis after urinating. It is impure (najis) and makes it obligatory to do wudu. End quote.
See also the answer to question no. 99507 .
And Allah knows best.