Introduction 

Ernst Haeckel classification had three kingdoms: Kingdom Animalia, Kingdom Plantae, and kingdom protista. Of these, kingdom protista was further classified into protozoa, fungi, bacteria, and other microorganisms.

On the other hand, R.H. Whittaker classified all the living organisms under 5 kingdoms. These kingdoms are Monera, Protista, Fungi, Plantae and Animalia. This system of classification is widely accepted and is used as a standard classification of living organisms. In Whittaker’s classification, kingdom protista consists of unicellular organisms with a well-developed nucleus—eukaryotes. Protista are the simplest form of eukaryotic organisms and possess autotrophic nature. They are mostly present in aquatic regions and are easily visible in freshwater, marine water, or moist soils. Some protists live a parasitic life, whereas saprophytic protists are also not uncommon. 

On the other hand, kingdom fungi consists of organisms that are multicellular eukaryotic but heterotrophic. Fungi can also be saprophytic as well as parasitic according to their mode of nutrition. They also possess a symbiotic relationship with organisms like the blue-green algae. 

Characteristics of Protista

The kingdom protista has various classes and subclasses that vary in their characteristics. The basic characteristics of kingdom protista are as follows:

1. The protists are generally aquatic. They are also present in moist soils.
2. The organisms of kingdom protista are eukaryotic unicellular. However, multicellular species are also not uncommon. As they are eukaryotic, they have a well-developed membrane-bound nucleus. 
3. They are usually autotrophic, i.e., they produce their food. However, they can also be saprophytic and also parasitic sometimes. 
4. Cilia and flagella are the locomotory organs in the protists. Some organisms also have pseudopodia for locomotion. 
5. The organisms of protista usually reproduce by asexual methods. However, sexual reproduction is also rarely possible.

Characteristics of Kingdom Fungi

The basic characteristics of fungi are as follows:

1. Kingdom fungi consists of organisms that are multicellular and eukaryotic.  
2. They are often heterotrophic, as they lack chlorophyll.
3. The fungi can reproduce both by sexual and asexual methods.
4. The asexual methods can be through spore formation. 
5. Sexual reproduction happens due to the production of pheromones.
6. The nuclear envelope of fungi does not dissolve during mitosis.

Difference between Protists and Fungi

The kingdom protista and fungi are very different both in the mode of nutrition and structure. The basic difference between the protists and fungi are as follows:

Difference between Monera, Protista, and Fungi

The first three of the five kingdoms vary significantly in their characteristics. The difference among them is as follows:

Significance of Protists

The protists being unicellular organisms are highly important for the ecosystem. 

• They produce half of the total oxygen on earth. Thus, they become one of the greatest sources of oxygen for every living organism on earth
• Protists are also involved in the recycling of certain nutrients essential for human survival
• They possess great significance in the medical field. Medicines for treating blood pressure, digestion problems, ulcers, and joint inflammations are derived from protists
• They are also used in laboratories for research
• Extraction from protists, specifically from red algae, is used in making puddings and ice creams. Thus, they are also an important industrial element
• They are an important part of the food chain

Significance of Fungi

Fungi are one of the most significant organisms on the planet. They play a vital role in the lives of human beings. The most important feature of kingdom fungi are as follows:

• They act as a recycling agent. Fungi, along with bacteria, are responsible for decomposing dead and decaying matter. Thus, they not only reduce unwanted waste by decomposing it but also increase soil fertility
• Fungi are the source of a variety of food for human beings. Mushrooms are one of the most popular and nutritious foods of kingdom fungi. Fungi are also involved in the production of other food and beverages such as beer, bread, cakes, cheese, etc. 

However, some kinds of mushrooms are poisonous, so one should properly examine them before eating any mushrooms. 

• Fungi have a vital role in the field of medicines as well. The most famous antibiotic, Penicillin, is derived from the fungus Penicillium. Caterpillar fungus has been a source of tonics in China since ancient times. There are also certain types of fungi that are beneficial in making medicines for the treatment of cancer

Conclusion 

The Protista and fungi are two large kingdoms in the five-kingdom classification proposed by R.H. Whittaker. They both are eukaryotic organisms. The protists are usually present in aquatic regions. The protists are autotrophic (other modes of nutrition such as saprophytic nutrition are not so uncommon,) but the fungi are heterotrophic and lack chlorophyll. Protists are unicellular, and fungi are multicellular organisms. They both possess high significance in the industrial as well as the pharmaceutical field. Fungi are widely used as a food and raw food product globally. On the other hand, protists contribute largely to the total oxygen production of the earth.