Difference between 一般 and 一样 meaning “same”
One difference is:

一般  could mean usual, average. As an adjective, you give a description of how something is comparing with the majority i.e, "same as average" or "not average".

For example, 
学霸就是学霸， 他的成绩可真不一般。 (The reputation of being the best at school, His grades are no ordinary.)

一般人的跑步速度是每小时25公里左右。(People's running speed is about 15 miles per hour)

牛顿的物理公式可以准确的描述我们一般的生活当中里的物理现象， 可是到了量子力学中， 就不行了。 (Newton's laws can accurately describe our day to day phenomena, But it would fail in quantum realm.)

一样 as an adjective is usually a description of states when comparing between two things. It is weird to use it to compare state of something with the state of the average.

一样 can sometimes mean exactly the same where as you cannot use 一般 to mean two things are exactly the same.