|Tirtha yatra refers to undertaking a pilgrimage to sacred places whereas parikrama (or pradakshina or circumambulation) means circling the sacred object.
Circumambulation however has deeper meaning in the religious space, connecting the pilgrim to the cosmos. Pradakshina is performed by circumambulating clockwise around a sacred person, sacred image, a sacred object or a temple in a clockwise direction.
Stoddard (1994: 18) identifies four key elements of pilgrimage: destination, movement, magnitude. and motivation. Preston (1992) adds "spiritual magnetism" to these critical components of pilgrimage. The most important component, of course, is the motivated pilgrim.
Circumambulation or parikrama involves all these elements, but it is the movement around, not toward a center. It is a movement encompassing an object: a temple, a holy site, a sacred mountain, a lake, a river, a city, and even includes circling around oneself.
Circumambulation (parikrama or pradakshina) is imbued with deep meaning for the devotee. In the Encyclopedia of Religion, Diana Eck lists several meanings of circumambulation. Included among them are: honoring, centering, bonding, setting apart, and reaffirmation of the sacred territorial claim. Additionally, circumambulation may symbolizes the fluidity of meaning characteristic of Hindu thought, such as: completeness yet continuity, fulfillment and quest, contentment and pursuit, comprehension and mystery. The pole star, for example, is the epitome of firmness in the Indian cosmology, yet the Hindu cosmos pulsates; it dissolves and re-emerges.
Most mandirs are furnished with passageways so as to facilitate circumambulation . Circumambulation takes the worshipper from the doorway of the sanctuary, housing the image of symbol of the Deity, around the sanctuary in a clockwise direction where further icons introduce other aspects of the divine.
An interesting story from the Hindu scriptures is Lord Ganesha circumambulating around His parents, which is accorded a higher status than circumambulating the entire Universe - signifying that the parents in Hindu ethos occupy the same status as God.
Source : Partial : http://www.colorado.edu/Conferences/pilgrimage/papers/Bhardwaj.html