Size

• Trees exceed 20 feet in height when fully grown, but shrubs rarely top 12 feet. Both are woody perennials and offer varying lifespans, depending on the species, but slow-growing trees tend to have a longer life span.
  
  

Appearance

• Shrubs naturally produce a number of stems that arise from the soil, but may be pruned into a single trunk specimen, which gives them the appearance of a tree. Without constant maintenance, shrubs will continue to try to produce multiple stems. Trees generally produce a single trunk.
  
  

Bark Comparison

• Shrubs have thin bark that offers a light covering over their woody stems. A tree produces bark that gains in thickness as the tree ages. Most tree bark takes on a grooved, aged appearance over time, but shrub bark rarely changes as the shrub ages.