It depends on the layout whether transition mouldings are needed. In the above posters hardwood to tile it's at an opening with the hardwood running with the opening and looks nice without moulding, but in open areas where there are large runs butting up to the two different floorings, transition mouldings are used when the hardwood is perpindicular or even at angles one to the other. The op has large areas kitchen, dining, foyer where depending on layout, more than likely would need mouldings where the two meet when perpindicular. An alternative to transitions is running a band of hardwood matching the flooring with the tile but perpindicular to the hardwood runs. Tha takes woodworking,(milling), that some installers wouldn't make time for.

I don't have a picture (I can grab get one if you like), but I did the same thing in my current project - new wood floor in the kitchen going right into existing in the dining room. The floor installer feathered some of the new boards into the dining room floor so it looked continuous, then I had all the existing floors sanded and refinished and stained the old+new 1 color. The result is a transition that looks completely continuous and uniform. Of course I had to refinish all my existing floors to do it. If you don't want to do that the only thing I can imagine working is a perpendicular strip to edge the new and old. It'd be impossible to match the old stain with new perfectly so you'd need something to separate the two. I have a spot in my house where the boards are mismatched so whomever installed it back in the day put a strip. I attached a picture of that.

I had the same problem. Had old strip flooring that was over 100 yrs old. At one point someone replaced a section with 3/4 thick wood floor but you wouldnt know until it was tore up. When I laid all the flooring an got to the the hallway I was up about 1/2 in. I shimmed up an 1/8 in then stripped a blank of the new floor on the table saw to build a thin transition piece. There is a slight raise but everything is the same level and looks nice. So in short just use a reducer.

So appreciate receiving feedback It means a LOT to me. God Bless all who have offered their expertise. This was a replacement cafe type door. That is there is a door on either side of the frame that meet in the middle when closed. I see now that with this replacement door there was a space between the tile and the door frame and he filled the space with grout.. Now there is grout between the tile and the door frame and there is some grout under the transition wood piece. Could this be the problem ? I am hesitant to call him back because I am not sure he is familiar with tile/wood flooring. He is primarily an outdoor contractor (septic systems etc.) who does indoor work during the winter. I cannot imagine another busy contractor would be willing to do this small (but important project). Neither my husband nor I are handy.