In civil contract In drag shows boundary wall while in BOQ item is boundary fence , is it confusing when we quote for fence in lump sum contract?

Its the tenderer/ contractor mistake and you will have to follow drawings , because its always mentioned  on Annex &Instructions to Bidder or as known as General Conditions those two conditions:

1.0              General

1.1              The Bill of Quantities shall be read in conjunction with the Conditions of Contract, Specifications, Drawings and Employer’s requirements and the Tenderer shall provide against the bill rates or in the prices for the full scope of the work covered by the Contract, no claim or variations shall be considered on account of the Tender’s failure to comply with this provision. The various documents collectively referred to herein as the Bill of Quantities shall jointly constitute the Bill of Quantities referred to in the Conditions of Contract and these preambles are to be read in conjunction with item descriptions in the Bill of Quantities.

1.2              Lump Sump values shall not be inserted where unit rates are applicable and the Tenderer shall ensure that identical items occurring in separate bills are not priced at different rates, unless this is the deliberate intention.

 The unique solution is trying to negotiate with the owner/consultant in order to understanding the situation or to mitigate it .