Both groups of people say that all humans and living entities on this planet are one family. A difference is that Arya Samaj does not believe in personalism. It is impersonalism and thus very dull, dry and eventually especially the younger generation will become fed up with their association.
The Hare Krishna Movement believes in impersonalism and personalism. It is energetic and young people become attractive to it because there is love and alot of seva to do for God, since you know He is a person, not some "light" or "power" only. These light and power is part of God the Supreme Person.
Sat-Cit-Ananda (Eternal-Knowledge-Bliss) is explained as:
Sat (Eternal Brahman, which is impersonal, done through Karma-yoga),
Sat-Cit (Eternal Brahman, Knowledge through the Supersoul, which is the localised aspect of God as Paramatma Who is there in all the bodies of the living entities sitting beside the soul as Witness, done through Jnana/Hatha-yoga),
Sat-Cit-Ananda (Eternal Brahman, Knowledge through the Supresoul, Bliss together with the Supreme Personality of Godhead, Bhagavan, which is the Supreme destination of the soul where he is in a loving relationship in the spiritual world which can be reached by stopping reincarnation, done through Bhakti-yoga)
The reason for this website not to hurt people's sentiment but to refute their enviousness towards Vaisnava's and Krishna, the Supreme Personality of Godhead.
Just because people of the Hare Krishna Movement are singing, dancing, eating and distributing prasadam as well as distributing Krishna Conscious literature doesn't mean that they will keep quite when you start using abusive language. Devotees of Krishna can tolerate if you insult them but if you insult the Guru-parampara and even Krishna Himself, then we will start to retaliate. Usually we do this with words, by quoting Vedic sastra.
In the Arya Samaj, there are people who cannot quote from their Rig, Sama, Atharva and Yajur Veda or from their Satyarth Prakas. Instead they start insulting. This is why not many people (except those who call them selves reformed hindo's) are attracted by them, yet they claim that all living entities (including all humans, thus also those who call them selves muslims, christians, white, black, man, woman etc) are one big happy family. Isn't that hypocrite? We live in the Kali Yuga, and this is one of the symptoms.