Rwanda → Tanzania
Rwanda plugs
Type C
Type E
Type F
Type GTanzania plugs
Type GShared plug type: G
Compatibility: Compatible
Voltage — Rwanda 230V — Tanzania 230V
Voltage is the same. Your devices should work normally.
Device compatibility (phones)
Phones almost always support 100–240V, so yours should work safely. Check your charger label to confirm.
You likely only need a plug adapter (if socket shapes differ). Voltage is close between these countries.