Limbo is derived from the Latin word limbus, which means edge. It is a concept devised by the Roman Catholic Church (although not an official part of its doctrine) to describe the situation of those whose spiritual status does not allow them to enter heaven or hell.
Essentially, there are two groups who are perceived as being in Limbo, namely unbaptized infants and righteous individuals from the past who lived too early to be eligible for the redemption of Christ.
The Beatific Vision is a concept in Christian theology. It refers to the direct visual perception of God which will be experienced after death by those entering heaven.
Generally, it is seen as a contrast to the knowledge of the presence of God which may be had on earth but which does not include a visual component.