While both of them have the meaning of "only", they are not exactly the same. The meaning is neutral and there is no judgement. It's usually used to explain one's inclination towards something. For example, if you say the following sentence You are merely stating the fact that "there is only one cake here".
All about か : It’s not only a question marker! – Japanese Ammo
Further information: Verbs Verbs are where most of the action in Japanese sentences takes place. They are the primary means for controlling levels of politeness in speech,… Japanese verbs inflect directly for tense, negation, mood, aspect, politeness, and honorific speech. Unlike English, conjugation of Japanese verbs is extremely regular, with few exceptions. The system takes some getting used to, but once the kana have been learned, a uniform pattern emerges. Despite being such, even they are somewhat regular in their irregularity.