There is a variation (a gap) in the abilities or skills of spoken English between the two students allotted to me. Should I seek uniformity??!!

Potential Solution 1: Diversity is inherent in nature and society. Embrace variation. Don’t be afraid of differences. Your embracing attitude towards differences / variation will be observed and learnt by the students. If you shun difference, if you are afraid of difference, it will be apparent to the student (consciously or unconsciously). Remember this “teaching experience” is as much of a learning experience for you as it is for the child. Be open about differences. Children already know it. But play a “What do we have in common game?” List all the things that the three or four of you (teacher included) have in common. Make one column per person. You will be surprised to see how much we have in common with each other.
Potential Solution 2: List the strengths of each child. Do not highlight weaknesses of the children. They know it already. They have been told that a 1000 times by all of society (including themselves). List their strengths. Keep asking till you find their strengths. Re-arrange your mind to see strengths (and not weaknesses and deficiencies). The glass is half-full (not half-empty. For example - Coming to school on time is discipline; helping a friend is cooperation; playing with friends is teamwork; sharing a toy, book, or homework demonstrates good social skill.
Potential Solution 3: Encourage children to talk in turns and play a game to facilitate children speaking in turns. Let the child with better skills help the child with weaker skills.
Potential Solution 4: Use this opportunity to build soft skills and listening skills in the children.