What is the difference between repudiated and retracted Confession?

Repudiated is a denied confession i.e accused denies  to have made the  confession at all.

Retracted  confession is the one  in  which accused avoids  to have made certain statement i.e accused  alleges that  what  is  said by the prosecution is  not  exactly what  he said or  meant  or  is the one in which accused agrees to have  made  in  the statement  but  says that  he  made it  by  inducement,  threat  or  promise.

What is evidentially value of repudiated  or retracted confession? 

Repudiated or retracted confession  may support  conviction if  the court  is fully satisfied in  all  circumstances of  the  case that  either of the two is true.   See Tuwamoi vs.  Uganda [1967] E.A  at pg  91. However  as a  matter  of prudence  conviction founded on repudiated or  retracted confession is required to be  corroborated. See  the decision of  Court of  Appeal  of Tanzania in  J.  Mwakatoka vs.  Republic  [1990] TLR  17  and  Ali Salehe Msuta vs.  Republic [1980] TLR 1.