The blazon on the lower arm and the number of buttons indicate that this is the uniform of the Royal Horse Artillery. The Woolwich on the second photo reinforces that opinion. This is the dress uniform as would be expected for a photo. They are both of the same man. I would guess that they were taken about 5 years apart in about 1875 or so. A real specialist could tell you more. The rank is that of a Lance-Corporal.
That applied to the two earlier photos. 3 more photos were posted whilst I was composing that - I am a bit slow. One is of the man in the dress uniform but now a Corporal with 4 long service stripes and what looks like the long-service medal. The next is of the same man, still later, in the undress uniform but now bearing the rank of Colour-Sergeant but I suspect they called it Battery Quartermaster - Sergeant BQMS. This might be about 1895-1900.
The one with the pillbox is probably taken after recruit training at Woolwich.
I hope any of this helps
