Question

what are the similarties and difference. between algae and green plant

Answer 1

Algae are simple organisms, sometimes unicellular, and even the largest types are relatively simple in structure.
A plant is any organism of the plant kingdom, as opposed to one of the animal kingdom or of the kingdoms Fungi, Protists, or Monera in the five-kingdom system of classification.
The main difference between the two is in their complexity. 

Answer 2

"algae and plant are similiar in that they can produce their own food from nutrients and sunlight by photosynthesis the main differences between the two is in their complexity.algae are simple organisms sometimes unicellularand even the largest type are relatively simple in structure ."