What are the similarities and differences between earth and early environment and earth's current environment?

The early Earth environment was characterized by a lack of free oxygen, extreme volcanic activity, and a predominantly toxic atmosphere composed of gases like methane and ammonia, which created conditions suitable for the emergence of life. In contrast, the current environment boasts a stable climate, abundant oxygen, and diverse ecosystems that support complex life forms. Both environments have undergone significant geological and biological changes over billions of years; however, the early Earth was more hostile and less conducive to life as we know it today. The transition to a more hospitable environment was largely driven by processes like photosynthesis, which increased oxygen levels and helped form the ozone layer.