The initial observation sets the scene for an experiment...what did you see? what was happening? How to improve it? And so on.
As the experiment proceeds you record all observations..what do you see?...what is happening? Etc.
At the end you note the final observations and how do they differ from the initial observations.
So, Initial observation is the observations you made initially of an experiment.
For example, a guy notices that his shower is covered in a strange green slime. His friend tells him that coconut juice will get rid of it. he decides to check this out by spraying half of the shower with coconut juice and other half with water after 3 days no change on either sides of the shower.The initial observation in that story would be that "the shower is covered in a strange green slime."
observation
It means what you saw during the experiment.
To give final result to our observation
Of the experiment, Observation. Of the entire process, conclusion.