Biology help- virusesWatch
Hope this helped.
1) Prokaryotic cells have a peptidoglycan layer, unlike Eukaryotes, meaning viruses infecting Prokaryotic cells (bacteriophages) have evolved a means of penetrating this layer - usually via a tail that injects through the layer into the cell membrane and peptidoglycan-degrading enzymes.
2) When bacteriophages inject their tails into the cell, they pump their genetic material into the cell and it is only the genetic material that enters the cell. Most (but not all) animal and plant viruses enter cells via membrane-fusion or endocytosis - which means the full viral capsid (and sometimes envelope) is engulfed in vesicles.
These are just trends though, there's always exceptions.