ものとして・つもりで: the difference
ものとしてN1
Meaning
Assuming, Supposing,
Past papers
Example
これ以上討議しても進展は見込めないものとして、これをもって会議はお開きとします。
Considering no further progress can be made in the discussion, with this the meeting is closed.
つもりでN2
Meaning
With the intention of doing, Instead of..., Act as if or pretend, Believing that..., Thinking that...
Past papers
Tested once in past papers
Example
ご馳走するつもりで行ったのに、おごってもらうことになった。
Despite going with the intention of treating everyone, they treated me.
How to tell them apart
「〜ものとして」: formal and official; assume it holds, then carry out the procedure.
「〜つもりで」: the speaker's own mental pretending, e.g. 「死んだつもりで頑張る」 (work as if my life were on the line).
「〜とみなして」: a firm legal or judgment-based ruling, 'regarded as'; lacks the flexible working assumption of 「ものとして」.