Interesting (both replies, that is). I really can't see bone-in/bone-out making the sort of difference that I am used to (Tandoori with a much deeper flavour, tikka mild and delicate), but regional variations are certainly a possibility. I cut my teeth on Tandoori Chicken in the Agra, Whitfield Street (London), but have no recollection of ever trying Chicken Tikka there; now in Kent, I often have Chicken Tikka as a starter, or Tandoori Chicken as a main course, and I can think of nowhere decent around here where the two are the same. I also use two different marinades when I make them myself, with the tikka marinade containing curd, chilli, curry masala, ginger, garlic, salt, sugar, oil and colouring whilst the tandoori marinade contains in addition black cumin, garam masala and sherry vinegar (the quantities and ratios vary as well).
Ray : yes, lamb tikka probably needs a fuller marinade than chicken, so I could imagine the full tandoori marinade being used for that.
** Phil.