hi nicholettes.
i've been to a couple of celebrations where they had the baptism and 1st birthday together. usually, for the baptism they only invite close friends and family members. they don't give out invitations for the baptism anymore but they usually inform the godparents personally. this makes this ceremony more intimate.
the invitation that is sent out usually announces the 1st birthday where everyone is invited to attend, family, friends, and officemates. so the focus of all the party items is more on the birthday, from the invitation, cake, tarp, decor, etc.
hope that helps.