The rotation and translation between 2 similar cubes in a scene

AFAIK, you can't have this kind of operation against the Transform component unless you create your own extension method.

Even if you could, I get very strange results. Maybe I am doing something wrong... But here is how you can compute the position and rotation difference between two transforms:

 Quaternion rotationDifference;
 Vector3 positionDifference;
 
 private void ComputeDifference( Transform other )
 {
     positionDifference = other.position - transform.position;
     rotationDifference = other.rotation * Quaternion.Inverse( transform.rotation );
 }
 
 public void ApplyDifference()
 {
     transform.position += positionDifference;
     transform.rotation = rotationDifference * transform.rotation;
 }

Thanks to @ETdoFresh, and his/her answer here, with additional functions, you can have the same result with TRS matrix

 Matrix4x4 trs;

 public void ComputeDifference( Transform other )
 {
     trs = Matrix4x4.TRS( other.position - transform.position, other.rotation * Quaternion.Inverse( transform.rotation ), Vector3.zero );
 }

 public void ApplyDifference()
 {
     transform.position += (Vector3) trs.GetColumn( 3 );
     transform.rotation = ExtractRotation( trs ) * transform.rotation;
 }

 public Vector3 GetPosition( Matrix4x4 m )
 {
     return new Vector3( m[0, 3], m[1, 3], m[2, 3] );
 }

 public Vector3 GetScale( Matrix4x4 m )
 {
     return new Vector3
         ( m.GetColumn( 0 ).magnitude, m.GetColumn( 1 ).magnitude, m.GetColumn( 2 ).magnitude );
 }

 public Quaternion ExtractRotation( Matrix4x4 m )
 {
     Vector3 s = GetScale(m);

     // Normalize Scale from Matrix4x4
     float m00 = m[0, 0] / s.x;
     float m01 = m[0, 1] / s.y;
     float m02 = m[0, 2] / s.z;
     float m10 = m[1, 0] / s.x;
     float m11 = m[1, 1] / s.y;
     float m12 = m[1, 2] / s.z;
     float m20 = m[2, 0] / s.x;
     float m21 = m[2, 1] / s.y;
     float m22 = m[2, 2] / s.z;

     Quaternion q = new Quaternion();
     q.w = Mathf.Sqrt( Mathf.Max( 0, 1 + m00 + m11 + m22 ) ) / 2;
     q.x = Mathf.Sqrt( Mathf.Max( 0, 1 + m00 - m11 - m22 ) ) / 2;
     q.y = Mathf.Sqrt( Mathf.Max( 0, 1 - m00 + m11 - m22 ) ) / 2;
     q.z = Mathf.Sqrt( Mathf.Max( 0, 1 - m00 - m11 + m22 ) ) / 2;
     q.x *= Mathf.Sign( q.x * ( m21 - m12 ) );
     q.y *= Mathf.Sign( q.y * ( m02 - m20 ) );
     q.z *= Mathf.Sign( q.z * ( m10 - m01 ) );

     // q.Normalize()
     float qMagnitude = Mathf.Sqrt(q.w * q.w + q.x * q.x + q.y * q.y + q.z * q.z);
     q.w /= qMagnitude;
     q.x /= qMagnitude;
     q.y /= qMagnitude;
     q.z /= qMagnitude;

     return q;
 }

It's not quite clear what you want to calculate here. A transform represents a 3d space. So you can define points in local space and they can be transferred into worldspace.

If you want the matrix which transforms from one space into the other you just have to combine the localToWorldMatrix of the source transform with the worldToLocalMatrix of the target transform. The resulting matrix allows you to directly transform a local space point from the source transform space into the target transform space.

 Matrix4x4 m = target.worldToLocalMatrix *  source.localToWorldMatrix;

Keep in mind if any of the two transforms changes you have to recalculate this matrix.