The main difference between "since" and "ever since" is the emphasis on the length of time that has passed since the event in question.
"Since" is generally used to indicate a specific point in time when an event occurred. For example, "I have been waiting since 3 PM." This implies that the wait started at 3 PM and has continued up to the present.
"Ever since" is used to indicate a longer period of time, often starting at a specific point in the past and continuing up to the present. For example, "I have been a vegetarian ever since I was a teenager." This implies that the speaker has been a vegetarian for a length of time since their teenage years, and continues to be one today.
So, while both "since" and "ever since" can indicate a connection between two events, "ever since" emphasizes the ongoing nature of that connection over time.
The phrases "even though" and "although" have very similar meanings and are often used interchangeably. Both phrases introduce a subordinate clause that contrasts with the main clause of the sentence.
However, there is a slight difference in emphasis between the two. "Even though" is considered to be slightly stronger and more emphatic than "although." This means that "even though" may convey a sense of surprise or greater contrast between the ideas than "although."
So while both phrases can be used interchangeably in many cases, "even though" may be better suited for situations where a more significant contrast is being made between the two ideas.
In short, the main difference between "even though" and "although" is that "even though" is slightly stronger and more emphatic than "although."