I understand what you mean by “church saints” and “tribulation saints.” There is certainly a distinction in Scripture between believers living at different times, and Revelation clearly speaks of saints who are present during the great tribulation.
But I would be careful about turning that into two different kinds of saints or two different kinds of salvation. Revelation says of those coming out of the great tribulation: “These are the ones who come out of the great tribulation, and washed their robes and made them white in the blood of the Lamb.” (Revelation 7:14, NKJV)
They are still the Lamb’s people. They are not presented as a lesser class of believers. Revelation also calls those living during this period “saints”: Here is the patience of the saints; here are those who keep the commandments of God and the faith of Jesus.”(Revelation 14:12, NKJV)
Their description is not based on a different gospel or a different salvation. They are people who keep God's commandments and have faith in Jesus. There is also the specific group of 144,000 who are sealed by God:
“Do not harm the earth, the sea, or the trees till we have sealed the servants of our God on their foreheads.”(Revelation 7:3, NKJV)
They are specifically identified as 144,000 from the tribes of Israel. Then John sees a great multitude from all nations coming out of the great tribulation. So Revelation does show different groups and different roles, but that does not automatically mean different kinds of salvation.
Jesus Himself spoke of His people as one flock: "And I have other sheep, which are not of this fold; them also I must bring in, and they will hear My voice; and there will be one flock and one shepherd.” (John 10:16, NKJV)
So I would say there are certainly believers who live in different periods and may have different roles in prophecy, but Scripture does not require us to divide God's faithful people into two separate classes of salvation called “church saints” and “tribulation saints.”
The important thing is what Jesus repeatedly taught: remain in Him, keep His commandments, overcome, and endure to the end.
“Be faithful until death, and I will give you the crown of life.” (Revelation 2:10, NKJV)
That promise is not limited to a particular generation. It is for those who remain faithful to Christ.