Airport arrival - Flight arriving at an airport.
Note that you may only enter India with the eVisa through these airports:

Ahmedabad, Amritsar, Bagdogra, Bengaluru, Calicut, Chennai, Chandigarh,Cochin, Coimbatore, Delhi, Gaya, Goa, Guwahati, Hyderabad, Jaipur, Kolkata, Lucknow, Mangalore, Mumbai, Nagpur, Pune, Tiruchirapalli, Trivandrum & Varanasi.

Seaport arrival is when you arrive in India via a boat/ferry/cruise ship at a seaport.

Entry is possible ONLY through these 3 seaports: Cochin, Goa and Mangalore.