I wanna know also how to draw these sketches step by step
You can find this information on the internet very easily. Just search for "oblique sketch vs isometric sketch".
"An oblique sketch puts more focus on the face or front of an object while an isometric sketch puts more focus on the edge of an object. To achieve this, oblique sketches are usually drawn using a 45 degree angle to render the 3rd dimension while isometric sketches are drawn using a 30 degree angle."