Capital T “Truth” is a concept that belongs to ideologies. I intentionally spell the word using the lowercase. Ideologies tend to deal in absolute or ultimate “Truths” as they see them as opposed to what I’ll call factual truth. These generally depend for their support upon the acceptance of premises that are not falsifiable, often a string of them with one following from the other. For example, God exists, homosexuality is a sin, etc.
Facts, on the other hand, are at least in principle verifiable. So, for example, while it is self-evidently “true” that planets have a shape to determine what shape a planet has requires some investigation. While an ideologue might cite a Bible verse to argue that it is flat or to argue that the sun moves around it, a “modernist” or “realist” wouldn’t assume this to be true without first acquiring evidence in support of the claim. Yes, it may turn out the evidence was misinterpreted or errors were made in its collection but this only reinforces modern scientific and philosophical skepticism regarding claims of absolute or ultimate “Truth”.
Things become even more complex when it comes to moral questions, but in so far as we can reach some kind of consensus regarding issues of what constitutes human wellbeing and flourishing it is still possible to develop hypotheses regarding what is likely to enhance or degrade them and measure the relative success of various approaches. For example, it will either be “true” (lower-case) or not that access to shelter and education tend to (probabilistically speaking) enhance, degrade, or have no effect upon human wellbeing.
So yes, both ideologies and “realism” are concerned with truth but they hardly approach it in the same way. Ideologies are absolutist and assume to know the truth often before they even know or understand the full extent of the questions while science is about trial and error. The former is either built upon or incorporates premises that cannot be tested while the latter allows for truth to be absolutely established only in very particular cases where the evidence allows for such a conclusion. Epistemologically science (or as you put it “realism”) also allows for facts about the world to be probabilistic. Indeed, when it comes to questions of human relations, virtually all non-ideological “truths” are considered probably true or true in most cases as opposed to absolutely or ultimately true. So, for example, the question of whether or not there is an objective morality matters to an ideologue and would likely be considered irrelevant or perhaps even the wrong question to a realist.