  We have performed photoemission and soft x-ray absorption studies of
pyrochlore-type Ru oxides, namely, the filling-control system
Sm$_{2-x}$Ca$_x$Ru$_2$O$_7$ and the bandwidth-control system
Sm$_{2-x}$Bi$_x$Ru$_2$O$_7$, which show insulator-to-metal transition with
increasing Ca and Bi concentration, respectively. Core levels and the O 2$p$
valence band in Sm$_{2-x}$Ca$_x$Ru$_2$O$_7$ show almost the same amount of
monotonous upward energy shifts with Ca concentration, which indicates that the
chemical potential is shifted downward due to hole doping. The Ru 4$d$ band in
Sm$_{2-x}$Ca$_x$Ru$_2$O$_7$ is also shifted toward the Fermi level ($E_F$) with
hole doping and the density of states (DOS) at $E_F$ increases. The core levels
in Sm$_{2-x}$Bi$_x$Ru$_2$O$_7$, on the other hand, do not show clear energy
shifts except for the Ru 3$d$ core level, whose line shape change also reflects
the increase of metallic screening with Bi concentration. We observe pronounced
spectral weight transfer from the incoherent to the coherent parts of the Ru 4d
$t_{2g}$ band with Bi concentration, which is expected for a bandwidth-control
Mott-Hubbard system. The increase of the DOS at $E_F$ is more abrupt in the
bandwidth-control Sm$_{2-x}$Bi$_x$Ru$_2$O$_7$ than in the filling-control
Sm$_{2-x}$Ca$_x$Ru$_2$O$_7$, in accordance with a recent theoretical
prediction. Effects of charge transfer between the Bi 6$sp$ band and the Ru
4$d$ band are also discussed.
