Poisonous
Poisonous (विषैला) describes something that is harmful if eaten, touched, or inhaled.
Some berries are poisonous.
Delhi NCR air is poisonous now a days.
Venomous
Venomous (ज़हरीला) describes animals that inject poison through a bite or sting.
A scorpion is venomous.
The snakes are venomous.