External Purity
Not eating onions, garlic, and meat; fasting, going to temples, performing rituals and pujas, and visiting holy places. These are some of the external purities which are basically shows or displays to make others think one is religious and pure.
Internal Purity
Being truthful, compassionate to everyone, charitable, living simply, and having a service to all nature are all internal purities. These qualities are all listed in the scriptures like the Bhagavad-Gita and Shrimad-Bhagavatam. This is what makes one truly religious and pure.
Conclusion
Wearing suchi (clean) clothes is useless if the mind is muchi (dirty).
Being a vegetarian, walking bear foot, chanting mantras, and wearing a tilak and dhoti is useless if one lies or treats others badly or does not do good to others.
We must first become internally pure, and then externally.